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 se han encontrado términos

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.