Pilar Cyst (Trichilemmal Cyst)

Definition

• Keratin-filled cyst originating from the outer root sheath of hair follicles. Commonly located on the scalp, presenting as a firm, mobile lump without a central punctum.

• Often mislabelled as an “epidermoid” or “sebaceous” cyst, but histologically distinct.

Epidemiology

• More frequent in middle-aged females

• Autosomal dominant trait: ~50% inheritance risk for offspring

Symptoms

• Typically asymptomatic

• Can become tender or painful if inflamed or infected

Management

• No mandatory removal unless symptomatic or bothersome

• Surgical excision under local anaesthesia if intervention is desired (preferably before rupture to minimise risk of scarring and infection)