Most common type of skin cystic lesion. Result of growth of epidermal cells within the dermis

Clinically, they are tethered to the epidermis. Enlargement and suppuration are the common reasons for presentation.

Treatment is by excision once infection has resolved.

Epidemiology

Epidermal cysts are:

• rare in children because they tend to grow slowly
• most common in young and middle-aged adults
• evenly distributed between the sexes
• often numerous in Gardener's syndrome and naevoid basal cell carcinoma

Pathogenesis

Epidermoid cysts are the result of growth of epidermal cells within the dermis. These cells lodge at this site as a consequence of three possible mechanisms:

• occlusion of pilosebaceous follicles; the most frequent cause
• penetrating injury resulting in implantation of epidermal cells into the dermis
• trapping of epidermal cells along embryonal fusion planes

Plantar epidermoid cysts have been linked to human papilloma virus infection.

PC

My be multiple lesions

Sites - anywhere on the body (rarely on palms, soles), commonly - trunk, neck, face, scalp