Epidermal cyst

Question 1

Aetiology of epidermoid cysts

Answer 1

The cyst lining is either normal epidermis (epidermoid cyst) or outer root sheath of hair follicle (pilar cyst)

Blocked sebaceous gland
Swollen hair follicle
Raised testosterone
Use of androgenic anabolic steroids
Genetic: Gardner’s syndrome, basal cell nevus syndrome
Pilar cysts often have an autosomal dominant inheritance

Question 1

What are epidermoid and pilar cysts

Answer 1

Epidermoid = Intradermal or SC tumours that originate in the dermis and contains keratin
Pilar cyst = originate from hair follicles (90% occur on scalp)

AKA epidermoid cyst, infundibular cyst, sebaceous cyst

Question 2

Symptoms of epidermoid cyst

Answer 2

Mobile mass
- face and trunk (anywhere except hands and soles of feet)
- Smooth
- Round
- central punctum

Contains:
- Small quantities of sebum
- Fibrous tissues and fluids
- Fatty (keratinous) substance - “cheesy” or foot odour smell
- Viscous, serosanguineous fluid (contains purulent, bloody material)

Question 3

Differentials for epidermal cysts

Answer 3

Lipoma (larger and soft)
Neurofibroma (hard and multiple)
Abscess (hot, red)

Question 4

Management for epidermoid cysts

Answer 4

Asymptomatic → Conservative

Symptomatic (painful, discomfort, infected) OR continued growth
- Incision and drainage
- Surgical excision: wide, minimal or punch biopsy
± curettage

Infection → Abx

Question 5

Complications of epidermal cysts

Answer 5

Inflammation
Infection
Rupture
Discomfort
Skin cancer