Cutaneous cysts

Synonyms

Cysts of skin, lips, mucous membrane.

Epidemiology

Frequent. M>F.

Definition

Cysts with epithelial lining (CEL): benign encapsulated firm or fluctuant lesions, containing material of various types (squamous material, sebum, sweat, hair, oily fluid).

Cysts without epithelial lining (pseudocysts) (PC): clinically are similar to CEL, but do not have a capsule.

Aetiology & Pathogenesis

Often superficial trauma, small injuries or subepidermal blistering diseases (milia due to blisters in porphyria cutanea tarda or epidermolysis).

Dispersion of epidermal or follicular germs or ductal structures into the dermis.

Signs & Symptoms

CEL: Round, slowly growing nodule, showing a central pore in some cases. Fixed or slightly movable beyond the overlying erythematous smooth skin surface.

PC: Translucent submucosal node developing on lip, tongue or buccal mucosa in the vicinity of salivary glands, following minor injury.

Milia (sing.milium) are tiny epidermal cysts arising from the infundibular portion of vellus hairs or dermal sweat ducts, without connection to the overlying epidermis. They present as yellowish tiny papules and usually disappear within a few weeks.

Ganglion: synovial pseudocyst with wall formed by fibrous tissue, surrounding amorphous myxoid material and with connect

Localisation

CEL: Preferred localisations are face, neck, capillitium and back.

PC: lips or mucous membranes, site of injury.

Classification

Epithelial cysts
- Sebaceous cysts
- Epidermal cysts
- Trichilemmal cysts
- Milia
- Hybrid cysts
Mucous (pseudo-) cysts (mucocele)
- Oral Mucous Cyst
- Lip cyst
- Digital Myxoid Cyst
- Synovial Cyst (Ganglion)

Laboratory & other workups

None or biopsy; diaphanoscopy (transluscency), ultrasound.

Dermatopathology

Cysts with Epithelial Lining (CEL): epithelial wall surrounding squamous debris with or without follicular structures. Reactive inflammatory infiltrate of the dermis, sometimes after rupture of wall with granulomatous features and multinucleated foreign body giant cells.

Cysts without Epithelial Lining (Pseudocysts) (PC): Fibrous wall including oily liquid or amorphous myxoid material.

Course

Sometimes self-healing by spontaneous regression, especially in mucous cysts.

Complications

CEL: Frequent rupture of the epithelial cyst wall with subsequent inflammatory reaction with or without bacterial superinfection leading to granulomatous foreign body reaction, abscess formation, bursting, and draining.

PC: none.

Diagnosis

Clinical and histologic features.

Differential diagnosis

Acneiform reactions, fibroma, lipoma, adnexal tumor.

Prevention & Therapy

Prevention not possible. Superinfected epidermal cysts develop in an abscess need an incision and tamponade. Antibiotics if severely superinfected and additional sorrounding tissue inflamed. Surgical removal including capsule in the native non-inflamed status. PC of mucous membranes may regress spontaneously.

3.2.9 Cutaneous cysts