A 38-year-old woman presented with unilateral lesions on the left side of the body and in the genital area. Clinically, the lesions showed a polymorphic pattern: brownish papules in the axilla, keratotic comedo-like papules on the hand and foot, and whitish papular plaques on the labia majora and anal canal. There was no family history of skin diseases. Histologically, cutaneous and mucosal specimens were characterized by acantholytic and dyskeratotic cells, corps ronds and grains in the parakeratotic zone, and by hyperkeratosis and parakeratosis. A diagnosis of epidermal naevus with acantholytic dyskeratosis was made.