Glossary

    A

    ACE
    Angiotensin Converting Enzyme
    ACR
    American College of Rheumatology
    ANA
    Antinuclear Antibodies
    ANA
    Anti-nuclear antibody
    ANCA
    Antineutrophile Cytoplasmatic Antibodies
    ANCA
    Anti-neutrophil cytoplasmic antibody
    AST
    Antistreptolysin Titre
    Abacavir
    An anti-retroviral medication to prevent or treat infection with HIV
    Abatacept
    A targeted treatment used in psoriatic arthropathy
    Aberrant
    Aberrant is an adjective pertaining to a deviation from normal
    Ablation
    Ablation is the destruction of tissue, often by cautery, cryotherapy or laser.
    Abscess
    A localized collection of pus in a cavity formed by disintegration or necrosis of tissues.
    Acantholysis
    The separation of keratinocytes of the epidermis by loss of intercellular connections permitting the cells to become round and hyaline. lmmunoreactive acantholysis is typical of pemphigus. Acantholysis occurs as a secondary change in viral bullae and in epithelial malignancies.
    Acanthoma
    Acanthoma is a benign tumour located in the prickle cell layer of the epidermis. There are several specific forms of acanthoma.
    Acanthosis
    Acanthosis is a histological term for thickening of the epidermis and elongation of the rete ridges due to thickening of the spinous layer and enlargement of rete pegs.
    Achromia
    Achromia means loss of colour. In the skin achromia is also called leukoderma or depigmentation and means a lack or absence of melanin.
    Aciclovir
    An anti-viral medication
    Acitretin
    A retinoid medication
    Acneiform
    Acneiform is an adjective used to describe a resemblance to acne.
    Acral
    Acral is an adjective relating to or involving a distal site, eg, ear, finger, toe, nose, penis and nipple.
    Acrochordon
    Acrochordon is a fibroepithelial polyp of the skin, commonly known as a skin tag.
    Acrocyanosis
    Reduced oxygenation of peripheries resulting in a blue discoloration
    Acroinfundibulum
    The upper portion of the follicular canal
    Acrokeratoderma
    Acrokeratoderma is skin thickening of the hands and feet, usually due to hyperkeratosis.
    Acrosyringeal
    Adj. relating to the intraepidermal spiral duct
    Actinic
    Actinic is an adjective pertaining to sun or ultraviolet radiation.
    Actinic keratosis
    Actinic keratosis is a scaly skin spot showing some atypia of keratinocytes caused by chronic sun exposure.
    Acuminate
    Adjective meaning rendered sharp or pointed
    Adenocarcinoma
    A malignant tumour with glands and gland-like structures
    Adenoma
    Adenoma is a benign epithelial tumour with glands and gland-like structures.
    Adenovirus
    A group of viruses which cause a variety of diseases
    Adhesion
    Adhesion is the process of the sticking together of components, eg, adhesion between keratinocytes.
    Adipocyte
    Adipocyte is a fat cell, also known as a lipocyte or adipose cell.
    Adjacent
    Adjacent is an adjective meaning to be next to or adjoining.
    Adjuvant
    Adjuvant is a noun and adjective meaning helper or helpful. An adjuvant is an extra agent added to improve efficacy, for example added to immunisations to improve the immune response. Adjuvant therapies are used after the main treatment for cancer to reduce the risk of recurrence and the chance of secondary tumours.
    Adnexal
    Adnexal is an adjective pertaining to an adnexa, an accessory or appendage. In dermatology, adnexal may pertain to hair, nail, sweat gland, etc.
    Aerobe
    Aerobe is an organism that requires oxygen.
    Aetiology
    Aetiology (American spelling etiology) is the study of causes and causation. Aetiology is also the cause of a situation, eg, the aetiology of a disease may be an infection.
    Agar
    A gel-like substance used to grow certain micro-organisms
    Aggregation
    Aggregation is a collection or clustering. For example, aspirin prevents platelet aggregation to form a clot.
    Agminate
    Gathered together in a group
    Agranulocytosis
    A reduced white cell count
    Albicans
    Turning or becoming white
    Alitretinoin
    A medication with activity on retinoid and rexinoid receptors
    Allele
    Allele is a variant form of a gene found on the same locus of a chromosome.
    Allergen
    Allergen is a substance capable of inducing an immediate or delayed hypersensitivity reaction (allergy).
    Allergy
    Allergy is a hypersensitivity reaction of which there are several different types
    Allodynia
    Pain arising from stimuli which do not normally induce pain
    Allopurinol
    A medication frequently used for the prophylaxis of gout, but which not infrequently causes skin rashes
    Alopecia
    Absence of hair from normally hairy areas of skin is termed alopecia. Alopecia can be diffuse or localised.
    SYN: baldness (of scalp)
    Amastigote
    A non-motile stage of certain protozoa
    Amelanotic
    Amelanotic is an adjective pertaining to a lack of melanin, the skin pigment.
    Amenorrhoea
    Amenorrhoea (American spelling amenorrhea) is the temporary or permanent absence of menstruation.
    Amiantacea
    Adjective meaning in the nature of asbestos (amiant
    Amikacin
    An antibiotic of the aminoglycoside family
    Amorphous
    Amorphous is an adjective describing a lack of form or shape.
    Amoxicillin
    An antibiotic of the penicillin family
    Amphotericin B
    A medication to treat certain fungal and protozoal infections
    Ampicillin
    An antibiotic of the penicillin family
    Amylase
    An enzyme found in the saliva and pancreatic fluid
    Amyloid / amyloidosis
    Amyloid is an abnormal aggregate of proteins deposited in tissue with characterstic staining and appearance on microscopy. Amyloidosis is the disease state.
    Anaemia
    Reduction in levels of haemoglobin below defined levels
    Anaerobe
    Anaerobe is an organism that does not require oxygen. It may be a facultative anaerobe meaning it tolerates oxygen in its environment, or a strict anaerobe meaning it is killed by oxygen.
    Anagen
    Anagen is the growth phase of the hair follicle.
    Analgesic
    A medication which relieves pain
    Anaphylaxis
    Anaphylaxis is an immediate hypersensitivity reaction that can be severe, and potentially fatal, in a sensitised individual.
    Anaplastic
    Anaplastic is an adjective used in histology to describe specific features usually indicative of malignancy. Anaplastic cells have irregular dark-staining nuclei, and are typically poorly differentiated.
    Androgenetic
    Relating to male sex hormones
    Anetoderma
    Atrophic skin patches, giving the palpating finger the same sensation as a hernial orifice
    Aneurysm
    An abnormal bulge in a blood vessel
    Angio-neurotic
    Adj. Relating to hereditary forms of angio-oedema
    Angiogenesis
    Angiogenesis is the formation of new blood vessels.
    Angioid
    Adjective meaning like or resembling blood vessels.
    Angioma
    Angioma is a benign collection of dilated congested blood vessels. On the skin an angioma typically presents as a red papule. The cherry angioma is a common example.
    Angioplasty
    A procedure restoring blood flow through an artery
    Angiotensin converting enzyme
    Part of the renin-angiotensin system regulating blood pressure. It may be raised in sarcoidosis
    Anhidrosis (adj. anhidrotic)
    Anhidrosis is the inability to sweat appropriately
    Annular
    Annular is an adjective describing a ring-like or circular shape. In dermatology this may be used for lesions grouped in a circle, or a ring-shaped lesion as in granuloma annulare.
    Anogenital
    Anogenital is the adjective pertaining to the area around the anus and genitals.
    Ante-cubital
    Adj. relating to the inner surface of the elbow
    Anterior
    Anterior is an adjective to describe being towards the front or before. In anatomy, anterior location means on the front (ventral) surface of a body part, eg, the anterior eye meaning the front of the eye.
    Anthropophilic
    An infection transmitted by another human
    Anti-SSA antibodies
    Antibody sometimes positive in lupus erythematosus and Sjogren’s syndrome.
    Anti-Sm antibodies
    Antibody sometimes positive in systemic lupus erythematosus
    Anti-cardiolipin antibodies
    Antibodies against cardiolipin which may be seen in various conditions including the antiphospholipid syndrome
    Anti-centromere antibodies
    Antibodies sometimes present in autoimmune diseases like Sjogren’s syndrome
    Anti-dsDNA antibodies
    Antibodies which may be positive in lupus erythematosus
    Anti-histone antibodies
    Antibodies which may be present in cases of drug-induced lupus erythematosus
    Anti-pruritic
    An agent which reduces itch
    Antigen
    Antigen (acronym Ag) is any substance that evokes an immediate or delayed immune response.
    Aphtha (adj. aphthous)
    Small ulcers of the mucous membranes are usually termed aphthae.
    SYN.: canker sore
    Aplasia
    Aplasia is the failure to develop, as in aplasia cutis.
    Apocrine
    Apocrine is an adjective pertaining to glands that form a secretion by releasing cytoplasm.
    Apoptosis
    Apoptosis is the regulated, normal physiological process by which a cell undergoes self destruction in response to signals from the cell nucleus.
    Appendages
    Appendages: plural of appendage; additional things or supplements. The skinl appendages are things additional to the epidermis and include eccrine (sweat) glands, apocrine (scent) glands, pilosebaceous structures (hair and oil glands) and nails.
    Apremilast
    A targeted treatment for psoriasis or psoriatic arthropathy
    Aquagenic
    An adjective describing a process caused or triggered by exposure to water
    Arachnids
    Arachnids: plural of arachnid; arthropods with four pairs of legs, eg, spiders, mites.
    Arciform
    Arciform is an adjective to describe an arched or bow shape.
    Arcuate
    Arcuate is an adjective to describe an arched or bow-shape.
    Areata
    Limited to a circumscribed area.
    Areola
    Areola is a circular area. In anatomy the areola is the pigmented circular area around the breast nipple. It is also used in dermatology to mean a red ring around an inflamed spot.
    Arteriopathy
    A disease of a blood vessel
    Arthralgia
    Pain and/or inflammation in a joint
    Arthropod
    Arthropod is an invertebrate animal with a segmented body, jointed limbs, and a hard shell that is shed periodically. Examples of an arthropod include an insect, spider, and crustacean.
    Asteatotic
    A form of dermatitis with marked dryness usually occurring on the lower legs
    Astringent
    Substance that is binding, contracting, constrictive or stypic.
    Atopic /Atopy
    Atopy is a genetic (inherited) tendency to develop allergies such as hay fever (allergic rhinitis), asthma, food allergies, and atopic dermatitis.
    Atrichia
    Atrichia is the absence of hair which can be either congenital or acquired.
    Atrophy / Atrophic / Atrophicans / Atrophoderma
    A diminution of a tissue.
    TYPES:
    -Dermal atrophy-e.g. focal dermal hypoplasia
    -Elastic tissue atropby-e.g. anetoderma
    -Epidermal atrophy-e.g. lichen sderosus
    -Subcutaneous atrophy-e.g. lipoatrophy
    Auspitz’s sign
    Pinpoint bleeding observed when the scale of a lesion of psoriasis is removed. The phenomenon is due to the rupture of capillaries which lie high in the papillary dermis beneath a thinned suprapapillary plate
    Auto-inoculation
    Spread of infection from one part of one’s body to another part
    Autoantibody
    Autoantibody is an immunoglobulin directed against a normal component of the host individual producing it (self, auto).
    Autoantigen
    Autoantigen is a normal self-protein targeted by a host antibody.
    Autoimmunity
    Autoimmunity is an immune reaction against 'self'
    Autoinflammatory
    Autoinflammatory is an adjective describing recurrent inflammatory episodes not associated with an autoimmune disease, malignancy, allergy, immunodeficiency or infection.
    Autologous
    Derived from the same individual
    Autosomal dominant
    Autosomal dominant is an adjective to describe a genetic disorder in which only one copy of the abnormal gene is required to cause the condition, and that gene is located on a non-sex chromosome.
    Autosomal recessive
    Autosomal recessive is an adjective to define a genetic disorder that requires both copies of a gene to be abnormal to cause the condition, and that gene is located on a non-sex chromosome.
    Axial
    Axial is an adjective pertaining to the axis, the centre or midline of a body about which it rotates; thus the axial skeleton is the cranium, sternum and spine.
    Axilla (adj. Axillary)
    The armpit
    Axonal
    Adj. Relating to the long process of a nerve
    Azathioprine
    An immunosuppressive medication
    Azithromycin
    A macrolide antibiotic
    Azoles
    A class of medications used to treat fungal and yeast infections

    B

    B lymphocyte
    B lymphocyte, also called a B cell, originates in the bone marrow and is normally involved in producing immunoglobulins to detect and combat infection.
    BCC
    Abbreviation for basal cell carcinoma.
    BRAF
    BRAF is a proto-oncogene that encodes a threonine protein kinase called B-Raf. It is essential for normal cell development and function however mutations in the BRAF gene may result in cancer.
    Bacillus
    A type of rod-shaped, Gram-positive bacterium
    Balanitis / balanoposthitis
    Inflammation of the glans penis /glans penis and foreskin
    Baldness
    Hairlessness, particularly of the scalp.
    Balloon cells (degeneration)
    Intracellular edema.
    Barbiturates
    A drug which suppresses the central nervous system
    Basal
    Pertaining to the base (e.g. of the epidermis)
    Basement membrane
    Basement membrane is the structure between an epithelium (epidermis in skin) and the underlying connective tissue (dermis in skin).
    Basophil (adj. Basophilic)
    Basophil is a granulocytic white blood cell (leukocyte) closely related to mast cells and eosinophils and involved in allergic disease. The cytoplasm of a basophil contains granules that stain blue with basic dyes, ie, basophilic.
    Basophilic degeneration
    Change in tinctorial properties of connective tissue, usually of elastic fibres or collagen.
    Bathing trunk nevus
    Giant congenital nevus.
    Belimumab
    A monoclonal antibody licensed for treatment of systemic lupus erythematosus
    Betel nut
    A seed of the areca palm which is chewed in some cultures. It may cause cancers.
    Biopsy
    Biopsy is a noun and verb pertaining to a tissue sample, eg, a dermatologist may take a skin biopsy, the dermatologist may biopsy the skin.
    Biovar
    A strain of organism which differs from others of the same family
    Blaschko line
    Blaschko line is an embryological clonal expansion line in the skin following a roughly linear, segmental pattern. A birthmark may be distributed along a Blaschko line.
    Bleb
    Bleb is a small thin-walled blister containing air or fluid.
    Blenorrh(o)ea
    A discharge, sometimes from the eye, which may be related to chlamydia infection
    Bleomycin
    A glycopeptide antibiotic used as a chemotherapy agent
    Blepharon / blepharitis
    The eyelid / inflammation of the eyelid
    Blister
    Superficial relatively thin walled structure containing air or fluid.
    Borreliosis
    A disease sometimes known as Lyme disease
    Botulinum toxin
    A protein which blocks the neuromuscular junction. It is used for various reasons in dermatology e.g. treatment of hyperhidrosis, anal fissures and cosmetic treatment of wrinkles.
    Bowenoid papulosis
    An intra-epithelial neoplasm probably caused by human papilloma virus and occurring in the ano-genital area
    Bowen’s disease
    A squamous cell carcinoma in situ
    Bradykinin
    A peptide with various physiological functions. It may mediate a form of angio-oedema
    Breslow thickness
    Breslow thickness, also called Breslow depth, is the thickness of an invasive melanoma in millimetres measured from the granular cell layer to the deepest tumour cell. Breslow thickness is an important prognostic factor so should be measured and recorded on the histology report.
    Bromhidrosis
    Bromhidrosis is an abnormal or offensive body odour.
    Bronchiectasis
    A pathological enlargement of some airways
    Bubo
    Enlarged lymph node.
    Bulla (adj. bullous)
    plural bullae
    Burrow
    A cuniculus, passage, or tunnel in the skin that houses a metazoal parasite, particularly the acarus of scabies.

    C

    CD-4
    A subset of T-lymphocytes
    CD-8
    A subset of T-lymphocytes
    CNS
    Central Nervous System
    CNS
    CNS is the acronym for central nervous system
    CPK
    Creatine Phosphokinase
    CRP
    C-reactive protein
    CRP
    CRP is the acronym for C-reactive protein; a nonspecific inflammatory marker protein produced by the liver and commonly measured in the blood. An elevated CRP in the blood is associated with infection, tumours, and inflammatory diseases.
    CSF
    Cerebrospinal Fluid
    CT
    CTis the acronym for computed tomography
    Cachexia
    Cachexia is a state of weight loss associated with anorexia, muscle and fat loss, poor quality of life, and fatigue. It is associated with cancer, AIDS, and chronic organ failure such as congestive cardiac failure or renal failure.
    Calcification /calcinosis
    Calcification is the process of depositing calcium salts in body tissues.
    Calcineurin-inhibitor
    Medications such as tacrolimus which inhibit T-lymphocytes. They are used in the treatment of inflammatory dermatoses
    Callus
    A localized callus is the hyperplasia of the stratum corneum (keratoderma) due to physical pressure.
    Candida / candidiasis
    A yeast which may cause infection of the skin or other tissues (candidiasis)
    Canities
    Gray or graying scalp hair.
    Carbamazepine
    An anti-convulsive medication which commonly causes skin rashes
    Carbuncle
    A necrotizing infection of skin and sub·cutaneous tissue composed of a group of furuncles (boils)
    Carcinoid
    A type of neuroendocrine tumour
    Carcinoma
    A malignancy (cancer) originating in epithelial cells
    Carotinosis
    Yellowish discoloration of the skin.
    Caseating necrosis / caseation
    Caseating necrosis is a histological term for a specific form of collagen destruction typically associated with granulomas
    Catagen
    Catagen is the short involutional phase of the hair cycle.
    Caudal
    Caudal is an adjective pertaining to the tail. A caudal location is on or near to the tail or base of the spine.
    Cautery
    Destructive procedure employing electricity (electrocautery) and chemicals (chemocautery).
    Cavernous
    Adjective meaning relating to a cave or hollow.
    Ceftriaxone
    An antibiotic of the cephalosporin family
    Cellulitis
    An inflammation of cellular tissue, particularly purulent inflammation of dermis, subcutaneous tissue, and soft tissue.
    Centrifugum / centrifugal
    Means fleeing from the center.
    Cephalosporin
    A family of broad-spectrum antibiotics
    Cervicitis
    An inflammation of the cervix
    Chancre
    A painless ulcer often on the genitalia which may indicate syphilis
    Checkpoint inhibitor
    Checkpoint inhibitor is a drug or agent that blocks an inhibitory checkpoint molecule protecting a tumour from immune attack. It is a form of immune therapy (immunotherapy).
    Cheiro- (adj.)
    Of the hand
    Cheloid
    See keloid
    Chemokine
    Chemokine is a chemotactic cytokine; a signalling molecule that induces chemotaxis in nearby cells. An inflammatory chemokine, for example, attracts leukocytes (white blood cells).
    Chemotaxis
    Chemotaxis is the movement of organisms, celsl, or cellular components, in response to a chemical stimulus.
    Chemotherapy
    Chemotherapy is an adjective and noun pertaining to the chemical treatment of disease, eg, chemotherapy drug, chemotherapy is the drug regime to treat cancer.
    Chlamydia
    A bacterium which may cause sexually transmitted infections
    Chloasma
    Patchy hyperpigmentation especially on the face.
    Chlorhexidine
    A topical antiseptic
    Cholinergic
    Cholinergic is an adjective pertaining to acetylcholine, a neurotransmitter.
    Chromatin
    Chromatin is the DNA and protein packaged to fit into the nucleus of a cell.
    Chromosome
    Chromosome is a long chain of genes; the entity carrying the genetic material of a cell (organism) which is passed to progeny, and is expressed as proteins for cellular functions.
    Chronic
    A term used to describe the long duration of a continuous illness
    Ciclopirox
    A topical anti-fungal treatment
    Ciclosporin
    A systemic immunosuppressive used for the treatment of psoriasis, atopic dermatitis and chronic urticaria
    Ciprofloxacin
    An antibiotic of the quinolone family
    Circumscribed / circumscripta
    Lesions that are sharply limited to an area by clean borders.
    Cirrhosis
    Late stage scarring process of the liver
    Clarithromycin
    A macrolide antibiotic
    Claudication
    A symptom of pain or loss of function due to impaired circulation often related to peripheral vascular disease
    Clavulanate /clavulanic acid
    A β-lactam antibiotic commonly co-administered with amoxicillin
    Climactericum
    Relating to the menopause. E.g. keratoderma climactericum
    Clotrimazole
    An anti-yeast treatment of the azole family
    Coagulation
    Coagulation is the process by which blood forms a clot.
    Colchicine
    A medication used to treat Behçet’s disease and periodic fever syndromes
    Collagen
    Collagen is a large family of proteins with a triple helix structure found in most tissues. In the skin, collagen is an important and major component of the dermis.
    Collarette
    A fine scaling on the border of a lesion. This is commonly seen in pityriasis rosea
    Collodion
    A membrane which rarely adheres to a neonate. It may indicate a tendency towards skin diseases such as lamellar ichthyosis
    Comedo /comedone
    A comedo is a plug of keratin and sebum in a dilated pilosebaceous orifice.
    SYN.: blackhead
    Commensal
    Commensal is an adjective and noun pertaining to a close relationship between unrelated organisms without harm to either, and sometimes with benefit to one or both.
    Comorbidity
    A condition that co-exists with another disease
    Complement
    Complement is a system of glycoproteins important in the innate immune system. Activation of the complement cascade results in enhancement of the cellular immune response.
    Compound naevus
    Compound naevus (American spelling nevus) is a benign melanocytic naevus in which melanocytes are found in both the epidermis and dermis.
    Computer tomography (CT)
    Computer tomography (CT) is a diagnostic radiology test that scans the body to produce cross-sectional images of the part.
    Concentric
    Concentric is an adjective pertaining to arrangement around a central point, eg, an archery or shooting target is concentric rings around the central bull's eye.
    Concomitant
    Concomitant is an adjective meaning accompanying or at the same time, simultaneous, eg, concomitant treatments means more than one treatment at the same time.
    Confluent
    Confluent is an adjective pertaining to confluence, flowing or coming together, eg, confluent pustules.
    Confocal microscopy
    An optical imaging technique giving detailed images of the skin in vivo
    Congelation / congelatio
    Freezing.
    Congenital
    Congenital is an adjective to mean present at birth, born with.
    Constriction
    Constriction is used to mean a narrowing of something, such as a blood vessel.
    Contracture
    Contracture is a permanent shortening of muscle, connective tissue, or skin typically resulting in deformity across a joint.
    Corium
    Portion of the skin, that is below the epidermis. The term dermis is used interchangeably with corium.
    Corneocyte
    Corneocyte is an epidermal cell (keratinocyte) in the stratum corneum (outermost layer of the epidermis) which normally lacks a nucleus.
    Cornoid
    Cornoid is an adjective meaning horn-like, eg, cornoid lamella is a thin horn-like layer.
    Corticosteroids
    A class of medication similar to cortisol used to treat inflammatory diseases. They are commonly used in topical preparations in dermatology
    Corynebacterium minutissimum
    AGram-positive bacterium which may cause skin infection
    Coxsackievirus
    An enterovirus
    Craquelé
    Scaling surface with cracks.
    Cream
    Cream, when used in dermatology, is a semi-solid formulation for topical application. A cream may be a water in oil (lipid) emulsion or lipid (oil) in water emulsion. Common usage also makes cream a verb, to apply a cream.
    Creatine kinase
    A muscle enzyme which may be raised in dermatomyositis
    Crisaborole
    A topical anti-inflammatory treatment
    Crotamiton
    A topical anti-pruritic and anti-scabetic treatment
    Crust
    A crust is an outer layer from the drying of exudate, secretion, or hemorrhagc.
    Cryoglobulin
    Cryoglobulin is an immunoglobulin that precipitates out in the blood on exposure to cold.
    Cryosection
    A technique to prepare histological specimens with a short turn-around. This enables intra-operative results and decision -making
    Cryosurgery / Cryotherapy
    A treatment using a very cold substance such as liquid nitrogen or dry ice (solid CO2). In dermatology, cryotherapy is often used to treat warts or actinic keratoses.
    Crypt
    Crypt is a chamber or room under the surface. So in dermatology, a crypt is a tube or recess extending down from the skin surface.
    Cubital
    Cubital is an adjective pertaining to the ulna bone in the forearm. The cubital (also called antecubital) fossa is the elbow crease anterior to (in front of) the elbow.
    Cumulative
    Cumulative is an adjective pertaining to accumulation
    Curet, curette, curettage
    Instrument and procedure that scrapes away tissue.
    Cutaneous (adj.)
    Of the skin
    Cuticle
    Cuticle is the outermost layer of a hair, and is also the transparent layer of dead cells that connects the proximal nailfold to the nail plate.
    Cutis
    Of the skin
    Cyanosis
    Cyanosis is the bluish colouration of the skin and mucous membranes due to deoxyhaemoglobin in the surface capillaries. This may be seen in either heart or lung disorders causing inadequate oxygenation, or when cold and the peripheral circulation is sluggish.
    Cyclophosphamide
    An immunosuppressive medication
    Cyst
    A cyst is any closed cavity or sac (normal or abnormal) with an epithelial, endothelial or membranous lining and containing fluid or semisolid material.
    Cytogenetic
    Cytogenetic is an adjective pertaining to cytogenetics, the study of chromosomes and their structure.
    Cytokeratin
    Cytokeratin is better known as keratin, a family of cytoplasmic proteins in epithelial cells.
    Cytokine
    Cytokine is a low molecular-weight molecule that acts as an intercellular messenger. Interleukins, interferons, colony-stimulating factors, and chemokines are examples of specific types of cytokine.
    Cytostatic
    The inhibition of cell growth or multiplication

    D

    DIF
    Direct Immuno Fluorescence
    DIF
    An abbreviation for direct immnofluorescence
    DLE
    Abbreviation for discoid lupus erythematosus
    DNA
    DNA is the acronym for deoxyribonucleic acid, a long nucleic acid chain that can encode genes, the famous double helix.
    DRESS syndrome
    A particular rash caused by medications
    Danazol
    A medication with anabolic steroid-like effects. It is used in the treatment of cholinergic urticarial and hereditary angio-oedema
    Dandruff
    Visible scaling of the scalp, not associated with a disease.
    Dapsone
    An antibiotic used in dermatology for the treatment of many skin conditions including dermatitis herpetiformis
    Darier sign
    Darier sign is positive when stroking the skin or lesion induces wealing
    Debridement
    Debridement is the process of removing infected or dead tissue to aid the healing process.
    Decubitus /decubitus ulcer
    An ulcer due to pressure. It is frequently seen in severely ill or immobile patients
    Demarcation
    Demarcation is a noun meaning the boundary or plane of separation between two areas.
    Demodex folliculorum
    A mite which lives in the hair follicle. It may cause demodicosis and may exacerbate rosacea
    Dendritic cell
    Dendritic cell has long finger-like processes called dendrites. Examples of a dendritic cell include a neurone, melanocyte, Langerhans cell, and some types of tissue macrophage (immune cell).
    Depigmentation
    A complete absence of skin pigmentation. This is to be differentiated from hypopigmentation, where there is reduced pigmentation
    Dermal naevus
    Dermal naevus (American spelling nevus) is a benign melanocytic naevus in which the melanocytes are entirely within the dermis. Dermal naevus is also called an intradermal naevus.
    Dermatitis
    Dermatitis is inflammation of the skin, but is mostly used more specifically as a synonym for eczema, ie, spongiotic inflammation of the epidermis.
    Dermatofibroma / dermatofibroscarcoma
    Dermatofibroma is a benign scar-like tumour of the skin. Dermatofibrosarcoma is considered a malignancy
    Dermatome
    Dermatome is the area of skin innervated by a single sensory spinal nerve. A dermatome is also a tool for taking fine slices of skin.
    Dermatopathology
    Dermatopathology is the study of the microscopic appearance of skin diseases.
    Dermatoscopy
    Dermatoscopy, also called dermoscopy, is the use of a dermatoscope, comprising a power source, light and magnification to examine the skin, hair and nails
    Dermatosis
    A general term encompassing any abnormality of the skin
    Dermis (adj. dermal)
    The deeper portion of the skin under the epidermis
    Dermographism
    Means “writing on the skin”. Dermographism may be black (metallic particles rubbed off) or urticarial (whealing in the precise form of scratching) or white (blanching that occurs upon stroke of skin affected by atopic dermatitis).
    Desensitisation
    Desensitisation (American spelling desensitization) is a process of reversing a hypersensitivity reaction such as an allergy.
    Desmoglein
    Desmoglein is one of a family of molecules involved in forming desmosomes, the intercellular junctions that stick skin cells (keratinocytes) together. There are three main types of desmoglein in the skin.
    Desmoplastic
    Desmoplastic is an adjective used in histology pertaining to desmoplasia, the presence of a fibrous connective tissue reaction typically related to specific tumours.
    Desmosome (adj. Desmosomal)
    Desmosome is a structure that holds adjacent epidermal skin cells (keratinocytes) tightly together, rather like cement between bricks.
    Desquamation
    Desquamation is the peeling of skin, coming off in scales, loss of squames.
    Diascopy
    Diascopy is a test using pressure from clear glass or plastic to see if a rash or lesion blanches. Diascopy also allows assessment of the underlying colour.
    Differential diagnosis
    Differential diagnosis is a list of conditions with similar symptoms or signs needed to be considered as possible diagnoses.
    Diffuse
    Diffuse is an adjective and verb pertaining to spread over a wide area. In dermatology, diffuse is used as an adjective to describe a change that is not localised or patchy, eg, diffuse alopecia compared to patchy alopecia.
    Digitate (adj.)
    Shaped like a hand e.g. digitate dermatosis
    Diphencyclopropenone /diphencyprone / DCP / DPC / DPCP
    An extreme allergen used for topical immunotherapy e.g. treatment of cutaneous metastases
    Diploid
    Diploid is an adjective describing a cell having two sets of chromosomes, as is typically seen in a normal somatic cell.
    Discoid
    Discoid is an adjective to describe being round like a disk. In dermatology it is used to describe lesions that are circular or oval and often well-defined, eg, discoid eczema and discoid lupus.
    Disseminated
    Disseminated is an adjective to describe being scattered or widespread and derives from the verb to disseminate meaning to scatter. Disseminated is therefore also the past tense of the verb. Examples in dermatology may include an infection that gained entry through the skin disseminated throughout the body
    Distal
    Distal is an adjective to describe being furthest from the point of origin or closest to the end. Anatomically this may mean being furthest from the centre of the body.
    Distribution
    Distribution is the localisation or pattern. The distribution of a dermatosis refers to the pattern or localisation of skin lesions, and can be quite characteristic for a specific condition.
    Doppler ultrasound
    A non-invasive imaging technique to measure blood flow
    Dorsal
    Dorsal is an adjective pertaining to the back or posterior part. A dorsal location means on the upper surface or back of a body part.
    Double-blind
    Double-blind is an adjective used to describe clinical trials in which neither the participants nor the researchers know which treatment or intervention has been selected for the individual, ie, both the assessor and the participant are blinded to the intervention.
    Doxycycline
    An antibiotic of the tetracycline family
    Dupilumab
    An inhibitor of interleukins 4 and 13 which is used to treat atopic dermatitis
    Duplex ultrasound
    Duplex ultrasound is an imaging test combining two types of ultrasound to produce a scan of blood flow in arteries and veins. Traditional ultrasound scans a fixed object (ie, the artery or vein), and is combined with a Doppler scan of moving objects (ie, blood flow). Uses for duplex ultrasonography scan include identification of a DVT, incompetent valves in varicose veins, or to map out vessels for sclerotherapy.
    Dysaesthesia
    Dysaesthesia (American spelling dysesthesia) literally means abnormal (dys) sensation (aesthesia) and describes unpleasant, uncomfortable sensations produced by ordinary stimuli. There are many specific types of dysaesthesia, eg, orodynia, pruritus ani, brachioradial pruritus, male genital dysaesthesia, etc.
    Dyshidrosis
    A blistering dermatitis sometimes known as pompholyx
    Dyskeratosis
    Dyskeratosis is a histological term for premature or altered (abnormal) keratinocyte differentiation.
    Dysmorphic
    Dysmorphic is an adjective pertaining to an anatomical malformation.
    Dysplasia
    Dysplasia is a histologic term for an atypical or abnormal appearance of a cell or tissue. In dermatopathology it is most commonly used to mean atypical cells in the epithelium.
    Dysplastic
    Dysplastic is an adjective pertaining to dysplasia, abnormal or atypical appearance of a cell or tissue.
    Dystrophy
    Dystrophy refers to degeneration or abnormal formation of tissue due to disease or malnutrition. A well-known example is muscular dytrophy caused by a genetic mutation. An example in dermatology is nail dystrophy, meaning a nail that did not develop normally or has become abnormal due to a disease such as tinea.

    E

    EASI
    EASI is the acronym for Eczema Area and Severity Index, a tool used for assessment and monitoring of atopic eczema.
    ECG
    ECG (American terminology EKG) is the acronym for electrocardiogram
    ELISA
    Enzyme-linked Immunosorbent Assay
    EMG
    Electromyogram
    ENA
    Extractable Nuclear Antibodies
    ESR
    Erythrocyte Sedimentation Rate
    ESR
    ESR is the acronym for erythrocyte sedimentation rate, a test of blood viscosity. The ESR is a nonspecific test often raised in inflammatory diseases and infections.
    Ecchymosis
    A macular red or purple or colored hemorrhage in skin or mucous membrane more than 2 mm in diameter.
    SYN: bruise
    Eccrine gland
    Eccrine gland is the common sweat gland in the skin.
    Ectatic (adj.)
    Dilated
    Ectodermal
    Ectodermal is an adjective pertaining to the ectoderm. An example is ectodermal dysplasia. The ectoderm is the outermost of the three primary germ layers of an embryo (the other two being mesoderm and endoderm). Ectoderm develops into epidermis and neural tissue.
    Ectoparasite
    A parasite living on the outside of the host’s body
    Ectopic
    Ectopic is an adjective pertaining to not being in the right place, eg, an ectopic pregnancy has developed somewhere other than inside the uterus.
    Ectropion
    Ectropion is a turned out part. Common usage has ectropion meaning the eversion (turning out) of a lower eyelid resulting in exposure of the inside surface of the eyelid.
    Eczema
    Eczema, also called dermatitis, is an inflammatory condition of the skin defined histologically by the presence of epidermal spongiosis.
    Edema
    See oedema
    Effluvium
    Effluvium, when used in dermatology, refers to diffuse hair loss of various causes. In general usage, an effluvium is an unpleasant gaseous smell.
    Elastic fibre
    Elastic fibre (American spelling fiber) is composed of elastin and microfibrils of fibrillin, collagen VI, and other proteins and glycoproteins. An elastic fibre demonstrates elasticity, the ability to stretch and return to the original.
    Elastolytic
    Elastolytic is an adjective pertaining to elastolysis, the breakdown and loss of elastic fibres.
    Elastosis
    Elastosis is a histological term for an increase in the elastic fibres in the skin.
    Elastotic
    Elastotic is an adjective used in histology pertaining to elastic tissue and fibres. Due to observed histological changes, elastotic often finds its way into the name of the condition as well.
    Electrocoagulation / electrocautery
    Destroying tissue by curdling (coagulation) with heat generated by a bipolar electrical instrument.
    Electrodesiccation
    Destroying tissue by drying it out (desiccation) The electrical instrument used involves high frequency, unidirectional current, that concentrate heat at a point in the form of a spark.
    Electron microscopy
    Electron microscopy is a laboratory tool used to examine extremely thin specimens with a beam of electrons passed through an electromagnetic lens. Electron microscopy allows visualisation of much smaller structures than light microscopy.
    Electrophoresis
    Electrophoresis is a laboratory technique to separate molecules by their electric charge and size using an electric field.
    Elevatum
    Adjective meaning raised.
    Embolus (adj. Embolic)
    Embolus is a small particle that has been carried through the bloodstream and blocks a small blood vessel. The particle is foreign to the bloodstream and examples include an air bubble, fat, clump of bacteria, or blood clot.
    Emollient
    Emollient derives from the Latin to soften, so an emollent is a moisturiser that softens the skin.
    Enanthem
    Enanthem, also called an enanthema, is a rash on mucous membranes.
    Encapsulated
    Encapsulated is an adjective and verb pertaining to being within a capsule. A medication may be encapsulated, ie, in a capsule form rather than a tablet. In histology encapsulated describes a pathological process being contained by a membrane or wall, eg, a cyst is encapsulated by the fibrous wall. Microorganisms can also be encapsulated by a protective thick mucoid or polysaccharide layer.
    Endemic
    Endemic is an adjective used to describe being constantly present in a population or region, eg, an endemic disease may be due to an infectious organism or arthropod that spreads an infection occurring in an area due to climatic factors.
    Endocrine
    Endocrine is an adjective pertaining to the production and release of secretions (hormones) directly into the blood.
    Endogenous
    Endogenous is an adjective to describe an origin from within. In medicine an endogenous cause for an illness means it has not been caused by an external agent or event, eg, atopic dermatitis is an example of an endogenous form of eczema.
    Endophytic (adj.)
    Growing inwards
    Endoscopy
    Endoscopy is the use of an endoscope, an instrument introduced into a body cavity or organ allowing direct visual examination.
    Enzyme
    Enzyme is a biological catalyst involved in biochemical reactions.
    Eosinophil
    Eosinophil is a type of granulocytic white blood cell (granular leukocyte) involved in the innate immune system primarily as defence against parasitic infections. Eosinophils are pro-inflammatory and are found in large numbers in allergic inflammation.
    Eosinophilia
    Eosinophilia is an increase in the number of eosinophils in the peripheral blood.
    Eosinophilic
    Eosinophilic is an adjective pertaining to staining red with the dye eosin on microscopy. Examples include the eosinophilic cytoplasmic granules seen in eosinophils, the eosinophilic stratum corneum of the epidermis, and normal eosinophilic collagen fibres in the dermis.
    Ephilides
    Ephilides: plural of ephelis
    Epidemic
    Epidemic is the sudden occurrence of a disease (or other event) in excess of that normally expected. Epidemic can be used as a noun or adjective, eg, a 'flu epidemic or epidemic typhus.
    Epidemiology
    Epidemiology is the study of the distribution of a disease and factors involved in the spread of that disease in populations.
    Epidermis
    Epidermis is the outer epithelial layer of the skin overlying in the dermis. It is mainly composed of keratinocytes, but also includes melanocytes, Merkel cells and other cell types in small numbers.
    Epidermolytic
    Epidermolytic is an adjective used in histology to describe loosening of the epidermis.
    Epidermotropism
    Epidermotropism is movement into or towards the epidermis. It is a histological term for the migration of cells into the epidermis typically seen in mycosis fungoides and Paget disease.
    Epididymo-orchitis
    Inflammation of the epididymis and testicle
    Epigenetics
    Epigenetics is the study of phenotypic change due to changes in gene expression without changes in the gene itself. An example is modification of DNA methylation.
    Epilation
    Removal of hair.
    Epithelioid cell
    Epithelioid cell is large and round with abundant eosinophilic cytoplasm, prominent vesicular nucleus, and large nucleolus.
    Epithelioma
    Neoplasm or overdevelopment of epithelial tissue.
    Epithelium (adj. Epithelial)
    A protective layer of cells on all body surfaces
    Eponychium
    Eponychium is the nail cuticle, the skin attaching the proximal nail-fold to the nail-plate.
    Erosion
    An erosion is a loss of the epidermis which heals without scarring.
    Erysipelas
    A superficial form of dermal infection
    Erythema
    The redness of the skin produced by vascular congestion or perfusion. Perivascular lymphocytic inflammation.
    Erythrocyanosis
    A condition marked by a red-purple color.
    Erythrocyte
    A red blood cell
    Erythroderma
    A generalized redness of the skin. It is often associated with desquamation, as in exfoliate dermatitis.
    Erythromycin
    An antibiotic of the macrolide family
    Eschar
    Eschar is a full thickness scab that develops in a healing wound. Examples include wounds caused by a thermal burn, cauterisation, or chemical burn. An eschar can be typical of some infections particularly rickettsia.
    Eukaryote
    Eukaryote is a cellular organism in which the genetic material is contained within a nucleus.
    Exacerbation
    Exacerbation is a noun meaning an aggravation, worsening, or flare up.
    Exanthem
    Exanthem is a widespread skin rash typically caused by a drug or infection, usually accompanied by systemic symptoms such as fever, malaise, and headache.
    Excision / Excisional biopsy
    Complete surgical removal of a lesion for microscopic evaluation.
    Excisional biopsy
    Excisional biopsy is the complete surgical removal of a lesion for diagnosis, treatment or both.
    Excoriation
    Excoriation, also called a scratch mark, is a loss of epidermis and a portion of the dermis due to scratching. An excoriation may be linear or punctate.
    Excoriation
    An excoriation is any loss of substance of skin produced by scratching.
    Exfoliation
    Exfoliation is the process of peeling or shedding of the epidermal stratum corneum. It may occur after skin inflammation, or be induced by chemicals or abrasion.
    Exfoliation
    Exfoliation is the splitting off or separation of the keratin and epidermal skin surface in scales or sheets.
    SYN.: desquamation
    Exocrine
    Secretion to the outside (as opposed to endocrine).
    Exocytosis
    Exocytosis is a histological term for the random migration of inflammatory cells, such as lymphocytes, neutrophils, basophils, into the epidermis. Exocytosis is induced by cytokine release in inflammatory processes of the epidermis.
    Exogenous
    Exogenous is an adjective pertaining to an outside influence or cause. In medicine an exogenous cause for an illness means the cause is not from within, eg, contact dermatitis is an example of an exogenous form of eczema.
    Extra-mammary
    Outside of the breast tissue
    Extravasation
    Extravasation is the leakage of fluid or cells from a blood vessel into body tissue, eg, extravsation of red blood cells results in a bruise.
    Exudate
    Exudate is the ooze typically seen in wounds, derived from blood, and composed of protein and blood cells. An exudate can be described as serous, purulent, sanguinous or serosanguinous.

    F

    FISH
    FISH is the acronym for fluorescent in situ (in-situ) hybridisation, a cytogenetic test used to detect chromosomal abnormalities.
    Fascicle
    Bunch of fibres.
    Fasciitis
    Inflamation of the fascia (fibrous tissue surrounding blood vessels, muscles and nerves)
    Favus
    A clinical type of fungal infection
    Ferritin
    A blood protein which is measured as a reflection of body iron stores
    Fetid
    Foul smelling
    Fibril
    Single fine thread structure.
    Fibroblast
    Fibroblast is the most numerous cell type seen in loose connective tissue. In the dermis, fibroblasts produce collagen, elastin, ground substance, and fibronectin.
    Fibrohistiocytic
    Adjective describing microscopic changes with fibroblast and macrophage-like differentiation
    Fibrosis
    Fibrosis is the formation of excessive fibrous collagen.
    Filament
    Filament is a thread-like structure or fiber.
    Filiform
    Filiform is an adjective pertaining to filament, a thread-like structure, eg, filiform wart or filiform papilla of the tongue.
    Finasteride
    A 5α-reductase inhibitor oral medication used to prevent further hair loss in androgenetic alopecia
    Fissure
    A fissure is any linear gap or slit in the skin surface.
    Fistula
    A fistula is an abnormal passage from a deep structure to the skin surface or between two deep structures. It is often lined with squamous epithelium.
    Fitzpatrick skin types
    A classification of how skin reacts to sun exposure. Type I is where the skin never tans but always burns on exposure and Type VI is where the skin never burns and always tans on sun exposure.
    Flexural
    Flexural is an adjective relating to a bend or fold. In the skin the backs of knees (popliteal fossae), the armpits (axillae), the antecubital (cubital) fossae and the groin are examples of flexural sites. Atopic dermatitis is described as having a flexural distribution on the limbs as it commonly involves the popliteal and antecubital (cubital) fossae.
    Fluconazole
    An anti-yeast medication of the azole family
    Fluorouracil / 5-fluorouracil
    A chemotherapy agent used for treating solid tumours, but also in a topical form for pre-cancers and cancers of the skin
    Foam cell
    Histiocyte that has imbibed lipids and thus come to appear bubbled.
    Foliaceus
    Leaflike.
    Follicle (adj. Follicular)
    In dermatology this usually means a hair follicle, eg, a follicular lesion is located within or around a hair follicle. However in histology follicular also pertains to lymphoid follicles and ovarian follicles.
    Folliculitis
    Inflammation of the follicle
    Fomites
    Objects which may carry infections
    Free radical
    Free radical is an unstable form of an atom with an unpaired electron, for example, a reactive oxygen species.
    Frenulum
    A ridge of tissue e.g. of the lip, tongue or penis
    Fungating
    Fungating is an adjective pertaining to a fungus. In dermatology, it is typically used to describe a tumour erupting like a mushroom or toadstool.
    Furuncle
    A localized pyogenic infection originating in a hair follicle.
    SYN., boil
    Fusiform
    Spindle-shaped

    G

    GI tract
    Gastrointestinal tract
    Gamete
    Gamete is a haploid cell (having one copy of each chromosome instead of two) for sexual reproduction. In the female this is an ovum (egg) produced in the ovaries, and in the male, sperm produced in the testes (testicles).
    Gammopathy
    Gammopathy is a condition characerised by excessive antibodies (gammaglobulins, immunoglobulins) in the blood. It is typically used for a monoclonal proliferation of gammaglobulins.
    Ganglion
    A swelling or cyst arising from the joint or tendon
    Gangrene / gangrenous
    Gangrene is the death of tissue, associated with loss of blood supply.
    Gene
    Gene is the biological unit of heredity. A gene is encoded in DNA or RNA, and is usually located on a chromosome in the genome.
    Generalised
    Generalised (American spelling generalized) is an adjective meaning widespread or extensive. A generalised rash is distributed over most of the body surface area. (generalized/widespread/disseminated).
    Genodermatosis
    Genodermatosis is a genetically determined skin condition.
    Genome
    Genome is an organism's complete set of genetic material. It includes all the genes and information required to construct that organism. In eukaryotes the genome is stored in the nucleus. Although a genome in a nucleus is constructed of double-stranded DNA, some viral genomes are made from single- or double-stranded RNA.
    Genotype
    Genotype is the genetic message at a specific gene locus or the whole genome. The genotype can be sequenced looking for mutations or identifying alleles at a locus. Mutations in the genotype may or may not affect the phenotype.
    Genotyping
    Genotyping is the process of determining and comparing genetic differences between individuals, using biological assays and nucleic acid sequencing.
    Geophilic
    An organism selectively preferring soil dwelling
    Germline
    Germline is a noun and adjective pertaining to the genetic material passed to offspring, the next generation. The germline is the cells that produce gametes, the cells by which genetic material is passed between generations. In humans, these gametes are the sperm in men and the ova (eggs) in women. Germline as an adjective describes the genetic material passed from a parent, eg, germline mutation meaning every cell in the offspring carries the same mutation.
    Gingivitis / gingivostomatitis
    Gingivitis: an inflammation of the gums

    Gingivostomatitis: an inflammation of the gums and mouth
    Glabella
    An area of skin between the eyebrows
    Glans (penis)
    The head/tip of the penis
    Glomus tumour
    A (usually) benign painful tumour arising from the glomus body
    Glucocorticosteroids
    See corticosteroids
    Gram stain / Gram positive / Gram negative
    A histological stain helpful in classifying bacteria
    Granular layer
    Granular layer of the epidermis (stratum granulosum) is characterised by flattened cells filled with dark granules containing keratohyaline protein.
    Granule
    Little grain.
    Granulocyte (adj. Granulocytic)
    Granulocyte is a type of white blood cell (leukocyte) with a cytoplasm filled with microscopic granules containing enzymes and other proteins important in innate immunity. Neutrophils, basophils and eosinophils are the three most common forms of granulocyte in the blood.
    Granuloma (adj. Granulomatous)
    Chronic inflammatory tissue composed of macrophages, fibroblasts, and granulation tissue.
    Granulomatous
    Granulomatous is an adjective pertaining to granulomas, a type of chronic inflammation characterised by histiocytes.
    Grenz zone
    Grenz zone is a histological term for an apparently uninvolved area (zone) of papillary dermis separating the epidermis from an inflammatory or tumour cell infiltrate in the dermis.
    Griseofulvin
    An antifungal medication
    Ground substance
    Ground substance is the gel component of the dermis. It contains hyaluronic acid, dermatan sulphate, chondroitin-6-sulphate, anionic polysaccharides, and glycosaminoglycans. It does not include the fibres such as collagen and elastin, or cells.
    Gumma
    A necrotic granuloma of tertiary syphilis.
    Guttata / guttate
    Drop-like spots.
    GvHD
    Graft versus Host Disease
    GvHD
    Abbreviation for graft versus host disease
    Gyrate
    Gyrate is an adjective meaning spiral-like or rotating. In dermatology it is used to describe a pattern that is convoluting, winding, or coiled.

    H

    HAART
    Highly Active Antiretroviral Therapy
    HE
    Ha(e)matoxylin Eosin
    HHV
    Abbreviation for human herpes virus
    HIV
    Human Immunodefiency Virus
    HIV
    HIV is an abbreviation for human immunodeficiency virus.
    HLA
    HLA is an abbreviation for human leukocyte antigen(s), a complex of proteins expressed on human cells that help the immune system to distinguish self. HLA is the human version of the Major Histocompatibility Complex (MHC). HLA typing is also known as tissue typing, and is important for matching organ donors and recipients. Specific HLA types can be associated with disease susceptibility risk.
    HPV
    Human Papilloma Virus
    HSV
    Abbreviation for herpes simplex virus
    Haemangioma
    A benign tumour of blood vessels
    Haematocrit
    Haematocrit (American spelling hematocrit) is defined as the ratio of the volume of red blood cells to the total volume of blood. It is measured by separating red blood cells from plasma by centrifugation.
    Haematogenous
    Haematogenous (American spelling hematogenous) is an adjective pertaining to blood, its production, constituents, dissemination, or derivation, eg, haematogenous spread of a cancer means cancer cells have been spread via the bloodstream.
    Haematoma
    A localized, tumor-like collection of blood.
    Haemochromatosis
    A condition leading to iron overload in the body
    Haemolysis
    Haemolysis (American spelling hemolysis) is the rupture or destruction of red blood cells.
    Haemorrhage
    Haemorrhage (American spelling hemorrhage) is a noun and verb pertaining to a bleed or to bleed.
    Haemosiderin
    A form of iron released from degenerate red blood cells. It can stain the skin
    Hair cycle
    Hair cycle consists of a growth phase (anagen)
    Hair pull test
    Hair pull test is used for assessing a patient complaining of hair loss. If more than 10% of hairs in a pulled bundle are removed, the result is considered abnormal (positive). None, one or two hairs removed when gently tugging on a bundle of 50-60 hairs is considered normal.
    Hamartoma
    Hamartoma is a benign overgrowth of a mature cell type normal to the site or organ. In the skin a hamartoma often presents as a birthmark (congenital naevus), but may first develop, appear, or be noticed in adult life (acquired). Examples include naevus sebaceous, follicular hamartoma, and chondroid syringoma.
    Haploid
    Haploid is an adjective describing a cell with only one set of chromosomes, as is typically seen in gametes (ova and sperm).
    Heliotrope
    A purple/pink flower. This term is used in dermatology to refer to the colour seen with the rash of dermatomyositis around the eys
    Helminth
    Helminth is a parasitic worm. Examples of a helminth include a tapeworm, liver fluke, roundworm, and leech.
    Hemiatrophy
    A one-sided reduction in size or growth
    Hemidesmosome
    Hemidesmosome is a structure in the basement-membrane zone, made by the epidermal basal keratinocytes, and involved in sticking the basal keratinocytes to the dermis.
    Hemifacial
    Affecting only one side of the face
    Hepatic
    Of the liver
    Herald patch
    A lesion occurring before a more generalized rash e.g. in pityriasis rosea
    Hereditary
    Hereditary is an adjective pertaining to inheritance. In medicine, it is used to describe a genetic (inherited) mutation or condition.
    Herpes
    A type of virus which may infect the skin or mucous membranes
    Herpetiform
    Herpetiform is an adjective meaning to resemble herpes, so is used to describe clustered vesicles and does not imply a viral origin.
    Heterogeneous
    Diverse in origin
    Hilar (adj.)
    Relating to the central portion of each lunch (the hilum)
    Hirsute / hirsutism
    Excess hair: see hypertrichosis
    Histamine
    Histamine, 2-[4-imadazolyl]ethylamine, is stored in the granules of mast cells and basophils, and released rapidly via an IgE-mediated mechanism during hypersensitivity and inflammation. Local histamine release causes capillary vasodilation and plasma leakage. In anaphylaxis large amounts of histamine are released with systemic effects on smooth muscle and blood pressure.
    Histiocyte
    Histiocyte is a tissue macrophage
    Histopathology
    The study of tissues under a microscope
    Homogenous
    Homogenous describes a thing or things as being the same throughout.
    Homozygous
    Homozygous is an adjective pertaining to homozygosity, identical alleles of a specific gene, eg, an autosomal recessive condition requires the relevant gene to be homozygous.
    Horn
    A keratosis which is taller than it is broad.
    Horny layer
    Horny layer of the epidermis (stratum corneum) consists of stacks of keratinised dead cells without nuclei. The top layer of these cells loosens and falls off.
    Human leukocyte antigen
    Human leukocyte antigen (acronym HLA) is a complex of proteins expressed on human cells that help the immune system to distinguish self from foreign.
    Hyalinisation / hyalinised
    Hyalinisation is the process of forming hyaline in the dermis resulting in a ground-glass appearance, a word used in dermatopathology.
    Hydrophilic
    Hydrophilic is an adjective pertaining to the ability to combine with or dissolve in water.
    Hydrophobic
    Hydrophobic is an adjective pertaining to the inability or failure to mix with water.
    Hydroxychloroquine
    An anti-malarial treatment used in dermatology for various diseases including lupus erythematosus
    Hyper(a)emic
    An abnormal increase in blood flow
    Hypercalc(a)emia
    An unusually high level of calcium
    Hyperglycaemia
    Increased blood glucose
    Hypergranulosis
    An increased number of cells in the granular layer of the skin
    Hyperhidrosis
    Hyperhidrosis is excessive sweating and be localised to one body site, eg, palms, or  generalised, affecting the whole body.
    Hyperkeratosis
    Hyperkeratosis is a thickening of the stratum corneum, the outermost layer of the skin.
    Hyperlipidaemia
    Hyperlipidaemia (American spelling hyperlipidemia) is a higher than normal blood level of one or more of the lipids (fats) such as cholesterol or triglycerides.
    Hyperpigmentation
    Hyperpigmentation is a darker colour than normal for that person or site, due to increased pigment. It can be localised or generalised.
    Hyperplasia (adj. hyperplastic)
    Hyperplasia is the enlargement of a tissue by an increase in cell numbers.
    Hypersensitivity
    Hypersensitivity (or allergy) is an exaggerated immune reaction to an allergen or antigen following sensitisation. There are several types of hypersensitivity reaction: type I (immediate); type II (cytotoxic); type III (immune complex); type IV (delayed, T-cell mediated). Non-allergic hypersensitivity is a pseudoallergy as it does not involve the immune system.
    Hypertrichosis
    Hypertrichosis is excessive hair growth, not in the patterned distribution of hirsutism. Hypertrichosis may be localised or generalised.
    Hypertrophy (adj. hypertrophic)
    Hypertrophy is excessive growth or enlargement.
    Hypha (plural hyphae)
    Branching filament seen in some fungi
    Hypochromic
    Paler than would be expected: see hypopigmentation
    Hypohidrosis
    Hypohidrosis is decreased sweating.
    Hypopigmentation
    Hypopigmentation is colour that is paler than normal for that person or site, due to reduced pigment. It may be generalised or localised.
    Hypotrichosis
    Hypotrichosis is a relative lack of hair growth, often congenital or genetic in origin.
    Hystrix
    Lesion with sharp keratotic spines.

    I

    IIF
    Indirect Immunofluorescence
    IIF
    Abbreviation for indirect immunofluorescence
    IV
    Abbreviation for intra-venous
    Iatrogenic
    Iatrogenic is an adjective describing an event or outcome as a result of a doctor's action. In dermatology, an example of an iatrogenic illness would be a rash due to prescription of a medicine.
    Idiopathic
    Idiopathic is an adjective pertaining to an unknown cause.
    Ig
    Abbreviation for immunoglobulin
    Imiquimod
    A topical medication which modifies the immune system and is used for the treatment of genital warts and pre-cancers or skin cancers
    Immunofluorescence
    A technique to stain molecules with fluorescent-labelled antibodies to highlight features under the microscope
    Immunohistochemistry
    A system of special stains used in histological tests
    Immunopathogenesis
    Immunopathogenesis is the process of disease development involving the immune system.
    Immunophenotyping
    Immunophenotyping is the identification of specific antigens or markers expressed by a cell, using antibodies (immunoglobulins).
    Immunosuppression / immunosuppressives
    Immunosuppression: a weakened immune system
    Immunosuppressives: medications to suppress parts of the immune system
    Impetiginisation / impetigo
    Impetiginisation (American spelling impetiginization) is the process of secondary bacterial infection of a rash.
    In situ
    In situ means 'in place'; an adjective and noun pertaining to being confined to the site of origin or placement, eg, pre-invasive phase as in melanoma in situ; the dressing remains in situ.
    Incarnatus
    Converted into flesh.
    Incisional biopsy
    Incisional biopsy is the surgical procedure to sample a selected portion of a lesion for evaluation by a pathologist.
    Indolent
    Without significant pain or discomfort.
    Induration / indurated (adj.)
    A hardening of the skin which may be caused by inflammation
    Infarct
    An area of coagulation necrosis due to local ischemia.
    Infestation
    Harboring metazoal (“animal”) parasites on or in the body.
    Inflammasome
    Inflammasome is an intracellular complex comprising a receptor, a caspase-1 enzyme, and an apoptosis-associated speck-like protein. It is part of the innate immune system involved in binding and eliminating microbes.
    Infundibulum
    Infundibulum is a funnel shaped passage. In the skin the hair follicle infundibulum is that part of the follicle above the level of the insertion of the sebaceous gland.
    Inguinal
    Relating to the groin
    Innate
    Innate is an adjective pertaining to being present from birth, inborn, is not acquired later in life.
    Inoculation
    Inoculation is the process of introducing microorganisms or cells to grow in culture medium or a living body. Inoculation is often used synonymously with immunisation (vaccination) using a live vaccine through abraded skin as was done for smallpox prophylaxis
    Intercellular
    Intercellular is an adjective meaning between cells.
    Interdigital
    Between the anatomical digits, i.e., fingers or toes.
    Interface dermatitis
    Interface dermatitis is a histological term describing inflammation at the junction (interface) between the epidermis and dermis. It may be lichenoid or vacuolar.
    Interleukin (abbreviation IL)
    Interleukin means between leukocytes
    Interscapular (adj)
    Between the shoulder blades
    Interstitial
    Interstitial is an adjective pertaining to the interstitium, the intercellular connective tissue.
    Intertriginous (adj)
    Relating to an area where two skin surfaces rub against each other e.g. groin
    Intertrigo
    Intertrigo is a rash affecting body folds due to friction between adjacent skin sites.
    Intracellular
    Intracellular is an adjective pertaining to the inside of a cell, within a cell.
    Intradermal naevus
    Intradermal naevus, also called a dermal naevus, (American spelling nevus) is a benign melanocytic naevus (mole) located entirely within the dermis.
    Intraepidermal
    Within the epidermis
    Intrathoracic
    Within the chest
    Intravascular
    Intravascular is an adjective meaning to be inside (within) a blood vessel or lymphatic vessel.
    Intrinsic
    Internal, or not caused by an external factor (opposite of extrinsic)
    Introitus vulvae
    The opening of the vagina
    Intron
    Intron is a sequence of DNA or RNA that is cut out of the RNA transcript before translation into a protein.
    Inverted
    Structure developing into the skin instead on top.
    Ipsilateral
    Ipsilateral is an adjective pertaining to being on the same side of the body.
    Isch(a)emia
    A restriction of blood flow to tissues
    Isomorphic phenomenon
    Isomorphic (eponymous name Koebner) phenomenon is the involvement at a site of skin trauma or injury by a pre-existing inflammatory skin condition.
    Itraconazole
    An anti-yeast medication of the azole family
    Ixodes
    A type of tick which may cause disease
    immunoglobulins
    Antibodies produced by plasma cells which are an important part of the immune system e.g. IgA, IgG, IgM

    J

    Jaundice
    Jaundice is the yellowing of skin and sclera due to a buildup of bile pigments in the blood (bilirubinaemia). This is usually due to biliary or liver disease.
    Junctional naevus
    Junctional naevus (American spelling nevus) is a benign melanocytic naevus (mole) composed of melanocytes only along the dermoepidermal junction.
    Juxta-articular
    Nearby or to the side of a joint.

    K

    KOH
    Chemical formula of potassium hydroxide
    Karyotype
    Karyotype is the number and appearance of chromosomes assessed during mitosis (cell division).
    Keloid (also cheloid)
    A keloid is an elevated progressive scar formation usually without regression.
    Keratin
    Keratin is a family of proteins produced by keratinocytes, and forming the bulk of the epidermis, hair and nails.
    Keratinized
    The process of developing keratin
    Keratinocyte
    Keratinocyte is the skin cell that is the major building block of the epidermis. It produces keratin.
    Keratoderma
    Hyperplasia of the stratum corneum.
    Keratoderma
    Keratoderma is thickening of the skin, typically of the palms and soles. Keratoderma may be diffuse or localised.
    Keratohyaline granules
    Specks within the cells of the stratum granulosum. They are correction precursor substances in the formation of finished keratin.
    Keratolytic
    A treatment which dissolves or reduces keratin
    Keratolytic
    Keratolytic is an adjective and noun pertaining to the softening or destruction of keratin.
    Keratosis / keratotic (adj.)
    A keratosisis a horny thickening of the skin.
    Kerion
    A kerion is a nodular inflammatory, pustular lesion, due to a fungus infection. Kerion Celsi.
    Ketoconazole
    An anti-yeast medication of the azole family
    Koebner / Köbner
    Koebner was a German dermatologist in the 19th century who first described the isomorphic response (in lichen planus or psoriasis) now often known eponymously as the Koebner phenomenon.
    Koilocyte
    Koilocyte is a histological term for a 'hollow' vacuolated squamous cell infected with the human papillomavirus.
    Kyphoscoliosis
    Abnormal curvature of the spine

    L

    Labia
    Latin for lips. Mainly used in dermatology for the folds of skin forming the vulva around the vaginal opening
    Lacuna
    Natural, pathologic or artificially created discontinuity.
    Lamella
    Lamella is a thin layer.
    Lamina densa
    Lamina densa is the middle layer of the basement membrane (zone) between the epidermis and dermis. It is found just below the lamina lucida and is mainly composed of type IV collagen.
    Langerhans cell
    Langerhans cell is a specialised dendritic cell that presents antigens to the immune system. The Langerhans cell is characterised on electron microscopy by cytoplasmic Birbeck granules.
    Langhans cell
    Foreign body type of giant cell.
    Lanugo hair
    Fine hair present on almost all parts of the body
    Laser
    Laser is an acronym for light amplification of stimulated emission of radiation. Many uses have been found for laser devices including as a treatment in dermatology.
    Lata
    Flat or broad.
    Latent
    Latent is an adjective pertaining to latency, being dormant or concealed.
    Lateral
    Lateral is an adjective relating to the side. In anatomy a lateral location means on or towards the side of a body part.
    Lenticular
    Shape or form of a lentil.
    Lentigo (plural lentigines)
    Lentigo is a pigmented flat or slightly raised skin lesion with a clearly defined edge.
    Lethal
    Deadly, fatal.
    Leukocytoclasis / leukocytoclastic (adj.)
    Leukocytoclasis is the breakdown of infiltrating neutrophils in inflammation.
    Leukoderma
    Leukoderma means white skin, specifically white skin due to the loss of skin melanin. Also known as achromia and depigmented skin.
    Leukonychia
    Leukonychia is a completely or partially white nail.
    Leukop(a)enia
    A reduction in the white cell count
    Leukoplakia
    White thickened patches in the mouth
    Leukotriene
    Leukotriene is a family of potent biological pro-inflammatory mediators. These mediators are produced in the body from arachidonic acid by the enzyme 5-lipoxygenase and are divided into groups according to their chemical structure.
    Levofloxacin
    A antibiotic of the quinolone family
    Lichenificatio n
    Lichenification is a chronic thickening of the epidermis with exaggeration of its normal markings, often as a result of scratching or rubbing.
    Lichenoid
    Lichenoid is an adjective meaning to resemble lichen. Clinically lichenoid describes papules or plaques that look stuck-on to the skin like lichen on a rock or tree. In histology however lichenoid describes a band-like inflammation in the upper dermis.
    Linear lesion
    Linear lesion is a skin change forming a line. A linear lesion may be due to an external cause such as scratching, contact dermatitis, or the Koebner phenomenon activating a pre-existing dermatosis. However a linear lesion may also be developmental following a Blaschko line, a dermatome, or a vascular or lymphatic vessel.
    Lipase
    A fat-digesting enzyme produced by the pancreas
    Lipoma
    A benign tumour of fat cells
    Lipophilic
    Tending to bind to lipids
    Liquefaction degeneration
    Disintegration or poor delineation of the basal cell layer of the epidermis.
    Livedo
    Livedo is a mottled, typically bluish, vascular pattern in the skin due to slowed or obstructed vascular flow.
    Lobulated
    Divided into aggregations (lobules)
    Lotion
    Lotion is a liquid formulation for topical use. A lotion is usually a simple suspension or solution. After application of a lotion, the liquid phase evaporates leaving the active ingredient on the skin surface.
    Lupoid
    Lupus-like condition, showing red-brown discoloration, usually due to a granulomas infiltrate.
    Lymph(o)edema
    A persistent swelling caused by dysfunction of the lymph vessels
    Lymphadenopathy
    Lymphadenopathy is the abnormal enlargement of lymph nodes.
    Lymphangitis
    An inflammation of the lymphatic system
    Lymphoma
    A malignancy of the lymphocytes
    Lymphop(a)enia
    A reduction in the lymphocyte count
    Lysosomal
    Lysosomal is an adjective pertaining to lysosomes, membrane-bound cytoplasmic organelles in cells that contain hydrolytic enzymes.

    M

    MCTD
    Mixed Connective Tissue Disease
    MEK
    MEK is the acronym for mitogen-activated, extracellular signal-regulated kinase, an enzyme in the MAPK signalling pathway which mediates cell growth and survival.
    MRI
    Magnetic Resonance Imaging
    MRI
    MRI is the abbreviation for magnetic resonance imaging; a medical imaging technique using a magnetic field, radiowaves and a computer to produce detailed images. MRI is useful for soft tissue injuries affecting muscles, tendons or ligaments, for assessing the brain and spinal cord, and for looking for tumours. MRI does not use x-rays.
    MRSA
    Abbreviation for methicillin resistant staphylococcus aureus
    MSH
    MSH is the abbreviation for melanocyte stimulating hormone, one of the protein products of the pro-opiomelanocortin gene. There are three forms of MSH: -alpha, -beta and -gamma, with alpha being the most active in humans. MSH-alpha has many effects including on the pigmentary and inflammatory systems as well as on body weight.
    Maceration
    Maceration is the process of softening. In dermatology, maceration describes moist peeling skin such as between the toes after inadequate drying.
    Macrolide
    A family of antibiotics
    Macrophage
    Macrophage literally means big eater, and is another name for the histiocyte, a monocyte that has settled in the tissues including the skin. The macrophage is an actively migratory and phagocytic antigen-presenting cell, important in type IV hypersensitivity reactions and granuloma formation.
    Macroscopic
    Macroscopic is an adjective meaning large enough to be visible with the naked eye.
    Macule
    A macule is a circumscribed area of skin different in
    colour or texture from its surrounding tissue. A maculopapular rash consists of macules and papules.
    Maculopapular
    Maculopapular is an adjective pertaining to both flat macules and bumpy papules.
    Madarosis
    Madarosis is the loss of either eyebrows, eyelashes, or both.
    Magnetic resonance imaging
    Magnetic resonance imaging (MRI) is a medical imaging technique using a magnetic field, radiowaves and a computer to produce detailed images. MRI is useful for soft tissue injuries affecting muscles, tendons or ligaments, for assessing the brain and spinal cord, and for finding tumours. MRI does not use x-rays.
    Malaise
    Malaise is a general feeling of unwellness or sickness.
    Malassezia
    A type of yeast which may cause infections
    Malformation
    Malformation is a congenital abnormality due to faulty development of a body part.
    Malleolus (pl. Malleoli)
    A bony projection of the ankle
    Malodour
    Malodour is a bad or unpleasant smell.
    Marginal
    Marginal is an adjective pertaining to the margin, being on the edge. In dermatology, the word 'marginal' may be used for being on the edge of a lesion or edge of a body part.
    Mast cell
    Mast cell is a granulocytic white blood cell found in the connective tissue. Mast cell granules release histamine and other mediators. The mast cell is particularly important in the immune response to parasitic infections, and is also activated in some allergic reactions.
    Matrix metalloproteinase
    Matrix metalloproteinase (acronym MMP) is a family of enzymes within the superfamily of matrixins involved in extracellular matrix regulation, inflammation, scarring and wound repair. The matrix metalloproteinase family can be divided into two major groups - those that breakdown collagen and those affecting other molecules.
    Matrix of nail
    Matrix of nail is the tissue from which the nail is formed. The dorsal (outer) nail plate is formed from the proximal nail matrix under the nail fold but the ventral (inner) nail plate is formed from the nail bed.
    Meatus (adj. Meatal)
    Passage or tunnel.
    Medial
    Medial is an adjective pertaining to the median, the midline or middle.
    Melanin
    Melanin is a family of biological pigments derived from the amino acid tyrosine, and produced by melanocytes.
    Melanocyte (adj. Melanocytic)
    Melanocyte is a dendritic cell found in the basal layer of the epidermis, and other sites. The epidermal melanocyte produces melanin to protect the skin from damage due to ultraviolet radiation.
    Melanocyte-stimulating hormone
    Melanocyte-stimulating hormone (acronym MSH) is one of the protein products of the pro-opiomelanocortin gene. There are three forms of MSH: -alpha, -beta and -gamma, with alpha being the most active in humans. MSH-alpha has many effects including on the pigmentary and inflammatory systems as well as on body weight.
    Melanoderma
    Melanoderma is patchy or diffuse darkening of the skin due to increased melanin.
    Melanoma (or malignant melanoma)
    A malignancy of the pigment cells of the skin
    Melanophage
    Melanophage is a histiocyte (macrophage) which has ingested melanin granules or fragments.
    Melanosome
    Melanosome is a cytoplasmic organelle involved in the synthesis, storage and transport of melanin, and found in melanocytes.
    Merkel cell
    Merkel cell is a neuroendocrine cell found in the epidermis. The exact function of the Merkel cell is not known but is thought to be involved in mechanoreception as it is associated with a nerve ending especially in highly tactile sites such as fingertips and lips.
    Messenger RNA
    Messenger RNA (acronym mRNA) is the molecule responsible for carrying genetic information from the DNA (following transcription) to the protein-synthesising ribosomes for translation.
    Metachromasia
    Changed color different from normal tincture (histology).
    Metaplasia
    Metaplasia is the transformation of one type of cell into another because of a changed environment.
    Metastasis
    The spread of malignant cells
    Methotrexate
    An immunosuppressive medication used for the treatment of psoriasis and atopic dermatitis
    Metronidazole
    An antibiotic and anti-protozoal medication
    Microabscess
    Microabscess is a tiny collection of neutrophils, eosinophils, or atypical cells, preferentially in the epidermis.
    Microarray
    Microarray is a laboratory tool used in the analysis of thousands of tiny samples of DNA, RNA or proteins.
    Microbiome
    Microbiome, also called microbiota, is the collection of microorganisms that normally inhabit an organ or site, eg, the skin microbiome.
    Microthrombi
    Small blood clots
    Midline
    Midline is an imaginary line through the middle of a structure such that the two sides are equal.
    Milium (plural milia)
    A milium is a tiny, white cyst containing lamellated keratin.
    Minocycline
    An antibiotic of the tetracycline family
    Mitotic index
    Mitotic index is a count of the number of mitotic figures visible on microscopy of a tissue section, giving an estimate of how fast the cells are dividing.
    Moniliasis
    Synonym for candidiasis
    Moniliform
    In the shape of a necklace.
    Monoclonal
    Monoclonal is an adjective pertaining to a single clone, a group of identical units derived from an original single cell. Monoclonal cells form from a single cell. Monoclonal antibodies are produced by a single clone of plasma cells and have identical antigen-recognising sequences.
    Monocyte
    Monocyte is a mononuclear white blood cell made in the bone marrow and found only in the bloodstream. A monocyte becomes a macrophage as it actively migrates through body tissues.
    Monogenic
    Monogenic is an adjective pertaining to a single gene.
    Monomorphic
    Monomorphic is an adjective pertaining to one shape or form, all components having the same or an essentially similar appearance. A monomorphic rash looks the same all over, compared to being dimorphic or polymorphic.
    Morbidity
    Morbidity is the state of being unwell.
    Morbilliform
    Morbilliform is an adjective pertaining to the eruption of measles, measles-like rashes. Typically a morbilliform rash is generalised and erythematous, with macules or papules.
    Morbus
    Disease, illness.
    Morphology
    Morphology is the structure and form of things, and also the study of the forms of things. In dermatology the description of an individual skin lesion is the lesion morphology.
    Mortality
    Mortality is the state of dying or death.
    Mottled
    Spotty coloration.
    Mucin
    Mucin is a normal component of the ground substance surrounding the cells and fibres of the dermis. Mucin is mainly composed of hyaluronic acid, and has a stringy clear appearance.
    Muco-cutaneous
    Involving the skin and mucous membrane
    Muco-purulent
    Containing mucus and pus
    Mucosa (adj. Mucosal)
    Mucosa, also called mucous membrane, is the moist lining of body cavities and passages that can be exposed to the external environment, eg, the mucosa of the mouth, nose, eyes, and ano-genital area.
    Multinucleate
    Multinucleate is an adjective used in histology to describe having two or more nuclei, eg, a multinucleate giant cell.
    Mupirocin
    A topical antibiotic used for fucidin-resistant staphylococci or MRSA
    Mutagen
    Mutagen is a physical or chemical agent that alters or changes genetic material
    Mutation
    Mutation is a permanent transmissible change in the genetic material, ie, a gene mutation, which may or may not have any visible effect on the phenotype. Common usage tends to mean a visible effect as in a disease-causing mutation.
    Myalgia
    Muscle pain
    Mycelium
    The vegetative part of a fungus
    Mycology
    The study of fungi
    Mycophenolate mofetil
    An immunsuppressive medication used for the treatment of atopic dermatitis and immunobullous disorders
    Mycoplasma
    A Gram-negative bacterium
    Myeloid
    Myeloid is an adjective pertaining to the bone marrow.
    Myopathy
    A disease of the muscle causing reduced function
    Myxoid
    Myxoid is an adjective meaning mucus-like, but rarely pertains to mucus itself, eg, digital myxoid cyst, myxoid degeneration.
    Myxoma
    A tumour of primitive connective tissue
    mRNA
    mRNA is the acronym for messenger RNA, the molecule responsible for carrying genetic information from the DNA (after transcription) to the protein-synthesising ribosomes for translation.
    microvascular
    Microvascular is an adjective pertaining to the smallest blood vessels, usually capillaries.

    N

    N(a)evoid
    N(a)evus-like.
    N(a)evus
    A mole
    NK cell
    NK cell is the acronym for a natural killer cell, a cytotoxic T-lymphocyte involved in the innate immune system to induce programmed cell death (apoptosis).
    NSAID
    Non-Steroidal Anti-inflammatory Drugs
    NSAID
    NSAID is an abbreviation for non-steroidal anti-inflammatory drug.
    Naso-labial (adj.)
    Relating to the crease between the nose and lip
    Natural killer (NK) cell
    Natural killer (NK) cell is a cytotoxic T lymphocyte involved in the innate immune system, able to induce programmed cell death (apoptosis) of cancer cells and cells infected with a virus.
    Necrobiosis
    Necrobiosis describes partial degeneration of tissue, less than complete necrosis. It is often used to refer to swelling and degeneration of collagen in granuloma annulare and necrobiosis lipoidica.
    Necrosis, necrolysis, necrotizing
    Necrosis is death and separation of tissue or cells.
    Neisseria
    A Gram-negative coccus which may cause gonorrh(o)ea
    Neonatal
    Neonatal is an adjective pertaining to newborns in the first 4 weeks after birth.
    Neoplasia
    A malignancy
    Neurofibroma
    A benign tumour of the nerve sheath
    Neuron
    Neuron, also spelled neurone, is a dendritic nerve cell involved in the conduction of electrical impulses to carry messages to other cells.
    Neuropathy
    Neuropathy is any disease, damage, or dysfunction, of the nervous system or nerves.
    Neutrophil (adj. Neutrophilic)
    Neutrophil, also known as a neutrophil leukocyte, polymorph, or neutrophilic polymorphonuclear leukocyte, is the most numerous type of granulocytic white blood cell (leukocyte). It is the first-line of defence in tissue damage and infection.
    Nikolsky sign
    Nikolsky sign is positive when slight rubbing of the skin results in exfoliation or shearing of the skin's outermost layer.
    Nodule (adj. nodular)
    A nodule is a solid mass of the skin which can be observed as an elevation or can be palpated. Usually, 0.5cm or more in diameter.
    Nosocomial
    Nosocomial is an adjective pertaining to a hospital, eg, a nosocomial infection is an infection acquired in hospital.
    Notalgia
    Notalgia means pain in the back, from the Greek 'nota' (back) and 'algia' (pain). In medicine, notalgia is used to describe pain, tingling or numbness of the back due to a neurological cause.
    Nucleotide
    Nucleotide is the building block of the nucleic acid chains DNA or RNA. A nucleotide consists of a base (adenine, thymine, guanine, cytosine, or uracil) plus a sugar molecule (ribose or deoxyribose) and phosphate groups(s).
    Nummular
    Nummular is an adjective pertaining to a coin, such as being coin-shaped.
    Nystatin
    A topical anti-fungal medication

    O

    Occipital
    Occipital is an adjective pertaining to the occiput, the back of the head. In surface anatomy it is used to describe the back of the head overlying the occipital bone.
    Occlusion
    Occlusion is the process of closing, blocking, or sealing. In medicine, occlusion may relate to a blood vessel, hollow organ or surface.
    Oedema (adj oedematous)
    Oedema (American spelling edema) is tissue swelling due to excess interstitial fluid.
    Oil drop
    Oil drop is a nail sign, also called a salmon patch, in psoriasis presenting as an orange or brown streak or spot under the nail plate due to white cells in the nail bed.
    Ointment
    Ointment is a semi-solid formulation for topical use based on lipids (oils) and so tends to have a greasy feel. The lack of water in the formulation means preservatives are rarely required.
    Oligo-
    Little, scanty, slight, small.
    Omalizumab
    A monoclonal antibody against the high affinity IgE receptor. It is used as a treatment for chronic urticaria
    Oncogene (adj. Oncogenic)
    Oncogene is a gene that codes for a protein that can promote the growth and proliferation of tumour cells.
    Onych- or onycho-
    Related to nail.
    Onychodystrophy
    An abnormality of the nail plate
    Onycholysis
    Onycholysis is the abnormal lifting of the nail plate from the distal nail bed, presenting as a larger than normal white or yellow area at the end of a nail plate.
    Onychomadesis
    A periodic shedding of the nails
    Onychomycosis
    A fungal infection of the nail
    Onychorrhexis
    Onychorrhexis is longitudinal ridging and fissuring of the nail plate typically seen with ageing and diffuse nail matrix diseases.
    Ophiasis
    A particular (often treatment-resistant) form of alopecia areata affecting the back of the scalp
    Organelle
    Organelle is a structurally discrete component of a cell that has a specific function.
    Orthokeratosis
    Orthokeratosis is a histological term for the normal stratum corneum consisting of keratinised cells not containing nuclei.
    Osteomyelitis
    An infection of the bone
    Osteoporosis
    A thinning of bone density
    Ostium (plural ostia)
    An opening into the body
    Otitis
    An inflammation of the ear

    P

    PAS
    Periodic Acid Schiff
    PAS
    An abbreviation for Periodic acid-Schiff, a special stain used in histology
    PASI
    PASI is the acronym for Psoriasis Area and Severity Index, and is used for assessment and monitoring of psoriasis.
    PCR
    Polymeras Chain Reaction
    PCR
    PCR is the abbreviation for polymerase chain reaction. PCR is used for the detection and amplification of specific DNA sequences useful in making a diagnosis and gene sequencing.
    PET
    PET is the abbreviation for positron emission tomography
    PUVA
    Psoralen UVA
    PUVA
    Abbreviation for psoralens-ultraviolet A. This is a form of photochemotherapy used for the treatment of psoriasis and cutaneous lymphoma
    Pachyonychia
    Pachyonychia means elephant nail, and is a congenital abnormal thickening of nail.
    Pagetoid
    Pagetoid is an adjective used in histology to describe a resemblance to Paget cells, their appearance or behaviour. Paget cells are large pale cells seen the epidermis in Paget disease.
    Palisading
    A histological phenomenon where cells line up
    Palmar
    Palmar is an adjective pertaining to the palm of the hand.
    Palmoplantar
    Palmoplantar is an adjective pertaining to the palms and soles.
    Palpation
    Palpation is the process of feeling or touching.
    Panniculitis
    An inflammation under the skin of fat cells
    Papilla
    Papilla is a small nipple-shaped protuberance. There are several types of papilla on the tongue surface.
    Papillary dermis
    Papillary dermis is the upper portion of the dermis just beneath the epidermis. It consists of thin irregularly arranged collagen fibres, thin elastic fibres and ground substance.
    Papilloma
    A nipple-like mass projecting from the surface of the skin.
    EXAMPLES,
    Dermal: A soft flesh-colored elevated tumor with a dermal component. Fibroma molle.
    Epidermal: Acrochordon or papillomatous seborrheic keratosis.
    Papillomatous
    Papillomatous is an adjective pertaining to a papilloma. Clinically it describes the bumpy elevated surface of a lesion such as a viral wart. Histologically papillomatous describes irregular surface folding.
    Papule
    A papule is a small solid elevation of the skin, less than 0.5 cm in diame1er.
    Epidermal papule: A papule composed of localized thickening of the epidermis or of the stratum corneum.
    Dermal papule: A papule composed of a localized solid thickening of the dermis produced by augmentation of normal structures, deposition of metabolic products, concentrations of cells or other pathologic changes.
    Inflammatory popule: A papule produced by inflammation of the dermis, epidermis, or both.
    Papulosquamous lesion: A papule that develops a reactive or degenerative epithelial component resulting in desquamation, which is the loss of epithelial cells or of stratum corneum (scaling).
    Wheal (Anglosaxon): An elevated compressible, transitory. white or pink papule or plaque of dermal edema.
    Papulopustule
    Papulopustule is a skin lesion with both papular and pustular components.
    Papulosquamous
    Papulosquamous is an adjective describing being scaly, raised and palpable, as in papules and plaques.
    Papulovesicle
    Papulovesicle is a skin lesion with both papular (small bumps) and vesicular (small blisters) components, typically a small bump with a tiny blister on top as seen in an insect bite.
    Parakeratosis
    Parakeratosis is a histological word for an abnormal stratum corneum in which the keratinised cells of the skin surface retain their nuclei.
    Paraneoplastic
    Paraneoplastic is an adjective describing being remote to but associated with a neoplasm. A paraneoplastic symptom or sign indicates the presence of an internal cancer.
    Paraproteinaemia
    Paraproteinaemia (American spelling paraproteinemia) is the presence of a monoclonal immunoglobulin in the blood due to a monoclonal gammopathy.
    Paronychia
    Paronychia literally means around the nail, and is an inflammatory process around the edge of a nail.
    Paste
    Paste is a semi-solid formulation for topical application, comprised mostly of a powder such as zinc oxide. The powder is mixed with water or oil in varying proportions to form either a greasy protective fatty paste that is very stiff, or a drying cooling paste that tends to be soothing. Medicaments may be added to the paste, eg, dithranol in Lassar paste in the Ingram regime.
    Patch
    A large macule, more than 2 cm in diameter.
    Pathergy
    Pathergy is the development or flare of skin lesions after minor trauma, such as a needle prick, typically seen in Behçet disease and pyoderma gangrenosum.
    Pathogen
    Pathogen is an organism that can cause disease. Examples of a pathogen may include a virus, protozoan, or yeast.
    Pathogenesis
    Pathogenesis is the origin, development, and maintenance of a disease.
    Pathognomonic
    Pathognomonic is an adjective meaning characteristic or distinctive. A pathognomonic symptom or sign is one so distinctive that it can be used to make a diagnosis.
    Pathophysiology
    Pathophysiology is the study of the functional changes in living tissue in a particular medical condition.
    Peduncle
    Peduncle is a stalk-like component of a lesion.
    Peptide
    Peptide is a short chain of amino acids, shorter than a protein.
    Perforating
    Perforating is a verb and adjective pertaining to perforation, penetration, the making of holes. In dermatology, perforating also describes conditions in which something penetrates through a layer as in a perforating dermatosis.
    Perifollicular
    Perifollicular is an adjective meaning close-to or surrounding a hair follicle(s).
    Perineum
    Perineum in the female is from the anus to the posterior fourchette of the vulva. In the male it is the area between the anus and scrotum. Common usage has widened use to include the perianal skin, groin folds, and vulva or scrotum.
    Periodic acid-Schiff (PAS) stain
    Useful additional stain to show fungi and natural mucopolisaccharides.
    Perioral
    Perioral is an adjective pertaining to the area close-to and around the mouth.
    Periorbital
    Periorbital is an adjective to describe being around the orbit or the eye.
    Periorificial
    Periorificial is an adjective pertaining to the area close-to or around an orifice such as the mouth, eyes, or anus.
    Peripheral
    Peripheral is an adjective pertaining to the outer edge.
    Periungual
    Periungual is an adjective pertaining to around a fingernail or toenail.
    Perivascular
    Perivascular is an adjective used in histology meaning close-to and around blood vessels.
    Permeability
    Permeability is the property of allowing diffusion, transit or passing through, porosity, eg, the permeability of a membrane.
    Perniosis
    An inflammatory disorder usually of the extremities triggered by the cold (SYN: chilblains)
    Petechia
    A punctate hemorrhagic spot 1 to 2 mm in diameter.
    Phagocyte
    Phagocyte is an immune cell that can surround, kill and ingest particles such as bacteria and other microorganisms or foreign matter, a process is called phagocytosis. A phagocyte can also boost immune responses. Examples of a phagocyte include a macrophage and neutrophil.
    Phagocytosis
    Phagocytosis is the process by which a cell engulfs and ingests a particle.
    Phenotype
    Measurable features of the organism that are expressed by its genotype in conjunction with environmental factors.
    Phimosis
    An abnormal tightening of the foreskin
    Phlebectasia
    Phlebectasia is the congenital widening (dilation) of a vein.
    Photoaging
    Photoaging (British spelling photoageing) is an acceleration of the skin changes of ageing caused by exposure to ultraviolet radiation especially sunlight.
    Photoallergen
    Photoallergen is a substance that causes an allergic reaction to sunlight after either topical contact or systemic exposure. A photoallergen may be a medication, food, plant, or other chemical.
    Photoallergy
    Photoallergy is a delayed hypersensitivity reaction to a substance after exposure to light. It can be due to topical or systemic contact with a photoallergen or photosensitiser such as a medication, plant or food.
    Photodynamic
    Photodynamic is an adjective pertaining to the activation or intensification of a reaction by exposure to light in a living system, eg, photodynamic therapy (PDT) applies a topical photosensitiser to increase the reaction to a laser or light.
    Photogenodermatoses
    Genetic conditions which cause abnormal reactions to light
    Photoprotection
    Photoprotection is the process of using physical or chemical agents to protect against light, eg, UPF50+ clothing and SPF50+ sunscreens provide photoprotection.
    Photosensitivity
    Photosensitivity is an unusual increase in the reactivity of the skin to sunlight.
    Phototoxicity
    Phototoxicity is a dose-related chemical-induced sensitivity to light that does not involve an immune reaction.
    Pilosebaceous unit
    Pilosebaceous unit consists of a hair follicle and sebaceous (oil) gland.
    Pimple
    Lay term for an ugly papule or pustule.
    Pit
    Pit is a depression, hole or indentation in a surface. To pit is also a verb, meaning to remove the stone of a fruit.
    Pityriasis
    Pityriasis is an adjective meaning finely scaly and is used to describe a bran-like fine powdery scale.
    Plantar
    Plantar is an adjective pertaining to the sole of the foot.
    Plaque
    An elevated area of skin 2 cm or more in diameter. Plaques may have the same subdivisions as mentioned above under papules.
    Plasma
    Plasma is the fluid component of blood or lymph, ie, that part of blood or lymph without the cells. Plasma is also a state of matter initially thought to only occur at extremely high temperatures but cold plasma has now been developed for use in medicine, eg, non-laser plasma skin rejuvenation. Plasma is also an adjective to describe a cell type, ie, plasma cell, an activated form of B-cell.
    Plasma cell
    Plasma cell is an activated tissue B lymphocyte (B cell) producing immunoglobulin in an immune response.
    Pleomorphism
    Pleomorphism is multiple different forms. It is commonly used in histology to mean wide variability in nuclear or cell morphology which typically indicates malignancy.
    Pluripotent cells
    Cells which may develop into any of the three cell lines
    Poikiloderma
    A dermatosis characterized by variegated cutaneous pigmentation, atrophy, and telangiectasia
    Poliosis
    Poliosis is a patch of depigmented hair.
    Polyclonal
    Produced by different B-lymphocytes
    Polycyclic
    Polycyclic is an adjective describing many circles, which may be used in dermatology to describe a rash composed of rings or partial ring-shaped lesions.
    Polygonal
    Polygonal is an adjective pertaining to many angles. A polygonal skin lesion has a non-geometric shape.
    Polymerase chain reaction
    Polymerase chain reaction (acronym PCR) is a laboratory tool for detecting and amplifying a specific DNA sequence. It is useful in making a diagnosis by detecting DNA sequences of viruses or bacteria such as HPV in cervical swabs or HSV in skin swabs.
    Polymorphism
    Polymorphism is many forms; in histology nuclear polymorphism means the cell nuclei are variable in shape or appearance, ie, many forms of the nucleus; in genetics a polymorphism is a chromosomal locus with more than two alleles in the general population, ie, many forms of the gene resulting in many forms of the protein product, ie, protein polymorphisms; a single nucleotide polymorphism (SNP) may change the pharmacodynamics or pharmacokinetics of a drug and hence the therapeutic response.
    Polyploid
    Polyploid is an adjective describing a cell with more than the normal two sets of chromosomes, typically seen in malignant cells.
    Pomade
    Pomade is a greasy or waxy perfumed ointment or gel usually used to style scalp or facial hair.
    Pore
    Passage or opening (ostium).
    Porphyrins / porphyria
    Porphyrins: a breakdown product of haemoglobin which can cause disease (porphyria) if they accumulate abnormally
    Positron emission tomography (PET)
    Positron emission tomography (acronym PET scan) is a nuclear medicine imaging test used for assessing metabolic activity in tissues. Prior to imaging, a radiotracer is introduced into the body by one of a variety of routes including injection. In dermatology a PET scan may be used to detect skin cancer metastases or assess response to treatment.
    Posterior
    Posterior is an adjective meaning behind or towards the back. In anatomy a posterior location means on the back of a body part (dorsal).
    Powder
    Powder is a pulverised solid, for example talc (a mineral) or corn starch (vegetable).
    Predilection
    Predilection is a preference.
    Predisposition
    Predisposition is the susceptibility to a disease or condition.
    Prednisolone
    A commonly used oral corticosteroid medication
    Prepuce
    The foreskin of the penis
    Proctitis
    Inflammation of the lining of the rectum
    Prodrome
    An early warning of the onset of a disease
    Prognosis
    The likely outcome of a particular disease
    Prophylactic
    An intervention designed to prevent a disease
    Protozoa
    Protozoa: plural of protozoan
    Proximal
    Proximal is an adjective pertaining to proximity, a location or distribution closest to a point of origin or attachment. In anatomy, proximal relates to the centre of the body, ie, A being proximal to B means A is closer to the centre of the body than B.
    Pruritus (adj. Pruritic)
    Pruritus is an irritating skin sensation which elicits the scratch response.
    SYN.: itching
    Pseudocyst
    Pseudocyst is a firm lesion that contains fluid or semi-fluid material but, unlike a true cyst, it is not surrounded by a capsule or wall.
    Pseudoepitheliomatous
    Pseudoepitheliomatous hyperplasia is a histological term for a harmless thickening of all layers of the epidermis that can resemble squamous cell carcinoma.
    Pseudohypha
    Pseudohypha is a branched filament produced by a yeast resembling a fungal hypha.
    Pseudolymphoma
    A tumour resembling a lymphoma
    Pseudomonas
    A Gram-negative bacterium
    Psoralens
    A medication activated by light used in the treatment of psoriasis
    Psoriasiform
    Psoriasiform is an adjective meaning to resemble psoriasis. Psoriasiform may be used clinically to describe psoriasis-like well-defined scaly skin patches, or histologically to describe regular psoriasis-like acanthosis of the epidermis but lacking the other typical histologic features of psoriasis.
    Psychodermatology
    Psychodermatology is the study of skin conditions associated with, caused by, or triggered by mental conditions. Psychodermatology includes conditions that are primarily psychiatric in origin; others where the skin condition causes a secondary psychiatric issue such as depression or anxiety; skin conditions that flare with stress and therefore require treatment of both the stress and the skin; skin symptoms that are neurological in origin; and skin conditions that are treated with psychotropic medications.
    Pterygium
    Pterygium is a wing of extra tissue. In dermatology, pterygium typically describes an abnormal fold of skin connecting to nail in lichen planus and scleroderma. More commonly a pterygium affects the eye.
    Punch biopsy
    Punch biopsy is an incisional biopsy of tissue obtained using a biopsy punch tool.
    Punctate
    Pointed or marked with dots.
    Purpura
    Discoloration of the skin or mucosa due to extravasation of blood.
    Purulent
    Discharging pus
    Pustule
    A visible accumulation of pus in the skin.
    Pyknosis
    Pyknosis is a histological term for the change seen in the nucleus of a cell undergoing apoptosis. It is characterised under the microscope as a shrinking and darkening of the nucleus.
    Pyoderma
    Pyoderma is any purulent skin disease, either bacterial or nonbacterial in origin.
    pH
    pH is a log scale defining hydrogen ion concentration and hence acidity/alkalinity in a solution. The scale ranges from 0 to 14, with 0 as most acidic and 14 as most alkaline. Water is pH 7, defined as a neutral solution.

    Q

    Quotidian
    Quotidian is an adjective meaning daily. Quotidian malaria is the form of malaria with daily fever spikes.

    R

    Rash
    Rash is an eruption of skin lesions which can be localised or widespread. Rash is also an adjective meaning impetuous or without thought.
    Raynaud phenomenon
    Raynaud phenomenon is a vasospastic response to cold in which fingers or toes turn white and numb, and are bluish on rewarming before returning to normal. It may be primary (unknown cause) or secondary to connective tissue diseases.
    Reagin
    IgE or other antibody-like substances in the blood.
    Renal
    Of the kidney
    Resistogram
    A laboratory test to evaluate the sensitivity/resistance of bacteria to commonly used antibiotics
    Rete ridge
    Rete ridge is an upward projection of connective tissue between epithelial rete pegs.
    Reticular dermis
    Reticular dermis is the deep part of the dermis, composed of coarse elastic fibres and thick collagen bundles parallel to the skin surface.
    Reticulate
    Reticulate derives from the Latin to mean a small net, and is used as an adjective to mean covered by a net or network.
    Retinoid
    Retinoid is an adjective and noun pertaining to a molecule resembling vitamin A, eg, a retinoid drug. Common usage makes retinoid a noun used for a family of drugs related to vitamin A, eg, a retinoid (drug).
    Retro-auricular
    Behind the ear
    RhF
    Rheumatoid Factor
    Rhino-conjunctivitis
    Inflammation of the upper respiratory tract and eyes
    Ribonucleic acid (RNA)
    Ribonucleic acid (acronym RNA) is a molecule involved in the coding, replication and expression of genes. There are several different types of RNA in a cell including messenger RNA (mRNA), ribosomal RNA, and transfer RNA (tRNA). DNA is transcribed into mRNA by enzymes that read one strand of DNA converting the deoxyribose sugar into ribose and substituting the thymine base (T) for a uracil base (U). Ribosomal RNA and tRNA are involved in translating the mRNA code to amino acids and synthesising a protein. Some viruses use double-stranded or single-stranded RNA instead of DNA as their genetic material.
    Rituximab
    A monoclonal antibody used in the treatment of pemphigus vulgaris
    Roseola
    Rose-red macules or patches.
    Rupioid
    Rupioid is an adjective to resemble rupia

    S

    SCLE
    Abbreviation for subacute cutaneous lupus erythematosus
    SCORAD
    SCORAD is a tool used for SCORing Atopic Dermatitis, and is used for assessment and monitoring.
    SCORTEN scale
    A severity and prognostic index for toxic epidermal necrolysis
    SLE
    Abbreviation for systemic lupus erythematosus
    SPF
    Sun Protection Factor
    SSSS
    Stapylococcal Scaled Skin Syndrome
    STI
    Sexually Transmitted Infection
    STI
    Abbreviation for sexually transmitted infection
    Scale
    A scale is a flat plate or flake of stratum corneum.
    Squama TYPES
    1) Collarette scale: Describes the fine, peripherally attached and centrally detached scale at the edge of an inflammatory lesion.
    EXAMPLE: Pityriasis rosea
    2) Furfuraceous Describes fine and loose scales.
    3) lchthyosiform: Describes large, polygonal scales - as in fish scales.
    4) Psoriasiform (resembling psoriasis): Describes a silvery, white. parakeratotic, lamellated scale similar to a scale of psoriasis.
    Scar
    A scar is the fibrous tissue replacing normal tissues destroyed by injury or disease.
    SYN.: cicatrix
    TYPES:
    1) Atrophic scar: Papyraceouos or cigarette paper scar- describes thin wrinkled scars.
    2) Cribriform scar: Describes a scar perforated with multiple small apertures.
    3) ) Hypertrophic scar: An elevated vascular scar with excessive growth of fibrous tissue.
    Scarlatiniform
    Scarlatiniform is an adjective meaning to resemble the rash of scarlet fever, typically a flat red rash.
    Scintigraphy
    A non-invasive imaging technique using radio-isotopes
    Sclerodactyly
    Sclerodactyly is the thickening and tightness of the skin of the fingers or toes, which can result in spindle-shaped digits.
    Sclerodermoid /sclerodermatous
    Resembling the thickened, hard skin of scleroderma
    Sclerosis
    Sclerosis is an induration or hardening of the skin. It is often due to fibrosis.
    Sclerosis
    Unusual hardening of a tissue
    Scratch
    Superficial mostly linear injury of the epidermis, reaching not deeper than to the papillary dermis.
    Scurf
    Obsolete term for scales or crusts on the scalp see dandruff).
    Scutulum
    Tiny concave crust.
    Seborrhoeic
    Seborrhoeic (American spelling seborrheic) is an adjective pertaining to seborrhoea or resembling seborrhoea. Use in dermatology does not always involve actual seborrhoea, including seborrhoeic area (where seborrhoeic glands are common), seborrhoeic dermatitis (typically involves seborrhoeic areas), and seborrhoeic keratosis (which can have a greasy appearance unrelated to seborrhoeic glands).
    Segmental
    Segmental is an adjective pertaining to a segment, a part or section. A segmental distribution in dermatology describes involvement of one or more dermatomes or Blashko lines.
    Self antigen
    A self antigen is part of the person's body that can induce an antibody response in some people. 
    Sensitisation
    Sensitisation (American spelling sensitization) refers to the process of becoming sensitised (allergic) to an agent.
    Sepsis
    Sepsis is a bacterial infection causing systemic toxic symptoms such as fever.
    Sequelae
    The consequences of a disease
    Serology
    The study of serum
    Serpentine
    Serpentine is an adjective pertaining to a serpent (snake)
    Shave biopsy
    Shave biopsy is a tissue sample obtained by a slice or cut made parallel to the surface of the surrounding skin. A shave biopsy may remove all or part of a lesion for diagnosis or cure.
    Single nucleotide polymorphism (SNP)
    Single nucleotide polymorphism is a single nucleotide substitution in a gene seen commonly in the general population resulting in an allele that may influence disease susceptibility.
    Sinus
    A sinus is a cavity or channel
    Soft tissue
    Soft tissue in the body includes tendons, ligaments, fascia, skin, fibrous tissues, fat, synovial membranes, muscles, nerves and blood vessels. It does not include the bony skeleton, teeth, nail, or hair.
    Somatic
    Somatic is an adjective pertaining to the body.
    Somatic mutation
    Somatic mutation is a gene mutation that has occurred any time after fertilisation and so affects only limited cells, but specifically not the gametes (sperm or ova). A somatic mutation is not inherited or passed on to offspring.
    Sonography
    Sonography, also called ultrasonography, is an imaging technique using echoes of ultrasound pulses to detect areas of different density in body tissues.
    Sore
    Boil, ulcer or other localized painful lesion of the skin.
    Spindle cell
    Spindle cell is a long thin cell. Many cell types may present as a spindle cell so it is a descriptive term used in histology.
    Spirochaete
    A bacterium which may cause syphilis
    Spongiosis
    Spongiosis is a histological term for intercellular swelling of the epidermis resembling a sponge.
    Spore
    Spore is a unicellular dormant form of a plant or micro-organism resistant to adverse conditions capable of germinating after dispersal in favourable situations. A spore may be fungal, protozoal, or bacterial, amongst others.
    Squama
    Squama (or squame) is a skin scale.
    Squamous cell
    Squamous cell is a flattened keratinocyte in the outermost layers of the epidermis or mucosa forming the surface scale (squames).
    Staphylococcus
    A Gram-positive bacterium: the commonest bacterial cause of skin infections
    Stasis
    Stasis means a lack of change, which in medicine can refer to the slowing or cessation of flow or movement. Stasis can be used as a noun as in vascular stasis, meaning a lack of blood flow resulting in pooling of blood, or as an adjective as in stasis dermatitis to refer to the skin rash due to the pooling of blood and lack of flow.
    Stenosis
    An unusual narrowing
    Stigmata
    Marks or wounds. In dermatology this usually refers to the hallmarks of a particular disease
    Stomatitis
    Inflammation of the mouth
    Stratum corneum
    Stratum corneum is the surface horny layer of the epidermis consisting of stacks of dead keratin-filled cells (keratinocytes) without nuclei.
    Stratum granulosum
    Stratum granulosum is the layer of the epidermis under the stratum corneum, and is characterised by flattened cells filled with dark granules containing keratohyaline protein.
    Stratum spinosum
    Stratum spinosum, also called the prickle cell layer, of the epidermis contains increasingly flat keratinocytes as they move upwards during maturation towards the surface. Desmosomes are prominent producing the spiny shape.
    Streptococcus
    A Gram-positive bacterium
    Stria (adj. Striate)
    A streak or band of linear, a1rophic, pink, purple or white lesions of the skin due to changes in connective tissue.
    Striate
    Striate is an adjective pertaining to striations, bands or stripes.
    Subacute
    Between acute and chronic
    Subcorneal
    Subcorneal is an adjective meaning beneath the stratum corneum of the epidermis, or under the cornea of the eye.
    Subcutaneous
    Subcutaneous is an adjective pertaining to under the skin, eg, subcutaneous fat, subcutaneous injection.
    Subcutis
    Subcutis is the fat layer beneath the dermis. It is also called subcutaneous fat or hypodermis.
    Subepidermal
    Subepidermal is an adjective pertaining to being under or below the epidermis.
    Submammary
    Submammary is an adjective pertaining to under the breast(s).
    Subungal
    Subungual means underneath the nail plate.
    Suppuration
    Producing pus
    Suprabasal
    Suprabasal is an adjective describing being above the lowest layer. In dermatology it usually pertains to being just above the basal layer of the epidermis.
    Susceptibility
    Susceptibility is a noun meaning the likelihood of succumbing to an influencing factor, eg, susceptibility to developing an infection or cancer, antibiotic susceptibility of a bacterial isolate.
    Sycosis
    Sycosis is a chronic pustular folliculitis and perifolliculitis involving the beard area.
    Syndrome
    Syndrome is a group of signs and symptoms that occur together and characterise a particular condition.
    Syringoma
    A benign tumour of the sweat glands
    Systemic
    Systemic is an adjective describing involvement of the body system as a whole.

    T

    T lymphocyte (T-cell)
    T lymphocyte, also called a T cell, is a type of immune cell that originates in the bone marrow, matures in the thymus, and circulates around the body. There are several specific types of T lymphocyte.
    T-lymphocytes
    A subset of lymphocytes important in many dermatological diseases e.g. allergic contact dermatitis
    TEN
    Toxic Epidermal Necrolysis
    TNF-α
    See tumour necrosis factor
    Target lesion
    Target lesion, also known as an iris lesion, has concentric rings like a dartboard or bull's eye appearance.
    Targeted therapy
    Targeted therapy is a drug or agent that targets a specific protein or gene, eg, targeted cancer therapy, where the target resides in or on a cancer cell.
    Telangiectasia
    A visible vascular lesion formed by dilation of small cutaneous blood vessels.
    Telogen
    Telogen is the resting phase of the hair cycle. Telogen hairs have a clubbed or bulbous tip and last for several months before falling out (shedding).
    Telomere
    Telomere is the cap on the end of a chromosome that protects the DNA from structural damage. A telomere is composed of proteins and thousands of repeats of the DNA sequence TTAGGG in humans. The telomere is important for accurate DNA replication during cell division. There is gradual loss of telomere length after each cell division until there is insufficient length to allow DNA duplication and the cell becomes senescent.
    Temporal
    Temporal is an adjective pertaining to the temple or to time. In surface anatomy, it describes the part of the side of the head overlying the temporal bone, ie the temple. It is also used in medicine to describe events related by time, eg, a temporal relationship between taking a medication and developing a rash.
    Teratogen
    Teratogen is an agent that can cause birth deformities.
    Terminal hair
    Terminal hair is the thick long hair that normally occurs on the scalp and, after puberty, in the armpits, beard and pubic area.
    Thrombocytop(a)enia
    An abnormal reduction in platelet numbers in the blood which may result in a bleeding tendency
    Thrombophlebitis
    An inflammation of the veins resulting in blockage
    Thrombosis / thrombotic (adj.)
    Thrombosis is the formation of a blood clot (thrombus) in the heart or blood vessels.
    Thrush
    A lay term for candidiasis
    Thyroiditis
    Inflammation of the thyroid gland
    Tinea
    A latin term literally meaning moth, but used in dermatology to signify a dermatophyte infection. It is usually used in conjunction with a site descriptor e.g. tinea manuum (hand); tinea pedis (foot).
    Titre
    Titre (American spelling titer) is an expression of concentration as the maximum dilution still showing activity.
    Topical
    Topical is an adjective pertaining to a topic. When used in a pharmaceutical sense it describes an application directly to a surface. Common usage makes it also a noun, eg, using a topical (agent).
    Trachyonychia
    Trachyonychia is rough nail(s) with excessive longitudinal ridging due to proximal nail matrix damage.
    Transdermal patch
    Transdermal patch is a drug delivery system applied to the skin surface with an adhesive from which a medication is absorbed through the skin into the systemic circulation, eg, oestrogen patches used during the menopause, GTN patches used to treat ischaemic heart disease.
    Transglutaminase
    A group of liver enzymes
    Translucent
    Translucent is an adjective pertaining to translucence, being partially or semi-transparent, eg, light can pass through a translucent membrane.
    Treponema
    A spiral-shaped bacterium which causes diseases such as syphilis
    Trich- or tricho-
    Related to hair.
    Trichomonas
    A single-cell flagellate protozoal parasite which may cause sexually transmitted infection
    Trichophton
    A family of fungi which commonly cause infection of the skin, hair and nails
    Trophic
    Trophic is an adjective derived from the Greek for nutrition. In dermatology trophic is usually applied to skin changes associated with numbness due to neurologic causes, but can also be used for changes due to pressure in vascular insufficiency and malnutrition.
    Tuberculid
    A reactive process related to tuberculosis
    Tumo(u)r
    A tumor is an enlargement of the tissues by normal or pathologic material or cells that form a mass. It may be inflammatory or benign or a malignant new growth of cells or tissue.
    Tumour necrosis factor-alpha (TNF- alpha)
    Tumour necrosis factor-alpha (acronym TNF-_) is a pro-inflammatory cytokine predominantly synthesised by macrophages. It can also cause tumour cell necrosis.
    Tyrosinase
    Tyrosinase is the enzyme that catalyzes the first step in the production of melanin and other pigments from the amino acid tyrosine.

    U

    Ubiquitous
    Everywhere
    Ulcer
    A skin ulcer is a defect or loss of dermis and epidermis producedby sloughing of necrotic tissue.
    Ultrasound
    Ultrasound is a high-frequency sound wave. Ultrasound is used in ultrasonography to detect areas of different density in a body tissue.
    Ultraviolet radiation (UVR)
    Ultraviolet radiation is that part of the sun's electromagnetic spectrum with a wavelength between 100 nm and 400 nm (ie, shorter than visible light). Ultraviolet radiation is classified in three parts; UVA (230-400 nm), UVB (290-320 nm), UVC (100-290 nm).
    Umbilicated
    Umbilicated is an adjective pertaining to a central dell, usually seen in a vesicle, papule or nodule such as molluscum contagiosum or herpes simplex.
    Urethral meatus
    The opening on the skin of the urethra leading from the bladder
    Urethritis
    An inflammation of the urethra
    Urticaria
    Urticaria, also called hives, is a family of disorders characterised by transient weals.
    Uveitis
    An inflammation of the middle layer of the eye

    V

    Vacuole (adj. Vacuolar)
    Vacuole is a membrane-bound fluid-filled cytoplasmic organelle formed from endoplasmic reticulum. On histology, vacuoles look like empty spaces.
    Vacuolisation
    Vacuolisation is the process of forming vacuoles, membrane-bound fluid-filled cytoplasmic organelles.
    Varicose / varicosity
    Enlarged, twisted veins
    Vasculitis
    An inflammation of the blood vessels
    Vasculopathy
    A disease of the blood vessels
    Vasodilator
    An agent which dilates blood vessels
    Vegetation
    A vegetation is a growth of pathologic tissue consisting of multiple closely set papillary masses.
    Vellus hair
    Vellus hair is the short, fine, light-coloured hair found over most of the body.
    Venereal
    Sexually transmitted
    Ventral
    Ventral is an adjective pertaining to the front. In anatomy a ventral location means on the belly, anterior surface of the trunk, or flexor surface of a limb.
    Venule
    Venule is the smallest type of vein that connects capillaries to the venous system.
    Verruca
    A verruca is an epidermal tumor caused by a papilloma virus. Verrucous describes a lesion with a warty surface.
    Verrucous
    Verrucous is an adjective pertaining to verruca, a wart. Verrucous means wart-like, having a thickened scaly undulating surface.
    Vertex
    Vertex is the highest point of the scalp where it changes direction from being horizontal to vertical.
    Vesicle
    Vesicle is a small blister, a circumscribed lesion less than 0.5 cm in diameter that contains liquid (clear, serous or haemorrhagic).
    Vesicle (adj. Vesicular)
    A vesicle is a circumscribed elevation of the skin less than 0.5 cm in diameter and containing a liquid.
    Vesiculobullous
    Vesiculobullous is an adjective describing the presence of both small and large blisters (vesicles and bullae).
    Vibex
    A vibex is a narrow linear mark, usually hemorrhage, from scratching.
    Violaceous
    Violaceous is an adjective describing a violet or purple hue.
    Viscosity
    Viscosity is a physical characteristic of a fluid describing the fluidity, thickness.
    Volar
    Volar refers to the hollow of the palm and sole but can also refer to the side of the adjoining skin, such as the fingers and forearm.
    Vulvitis
    Inflammation of the vulva

    W

    W(h)eal
    An elevated white compressible, evanescent area produced by dermal edema. It is often surrounded by a red, axon-mediated flare.
    Warty
    Warty is an adjective pertaining to a wart, a wart-like surface.
    Well-defined
    Well-defined is an adjective used to describe having a clear sharp border separating it from its surrounds.
    Wickham’s striae
    White lines seen on the top of papules in lichen planus
    Wood lamp
    Wood lamps emit long wavelength UVA and is used to examine skin pigment changes,( eg, vitiligo or melasma) and fluorescent infections such as cat ringworm.

    X

    Xanthelasma
    A yellow, benign tumour composed of cholesterol, often seen around the eyes.
    Xerosis / xeroderma
    Xerosis is a name for abnormally dry skin.

    Y

    No Terms found

    Z

    Zona
    Girdle or belt.
    Zoophilic
    An infection transmitted by an animal
    Zosteriform
    Zosteriform is an adjective pertaining to herpes zoster, zoster-like, unilateral and restricted to a dermatome or distribution of a single spinal nerve.