Pigmented hairy epidermal nevus (Becker).

The pigmented hairy epidermal nevus (Becker) is a variety of epidermal nevus in which epidermal thickening may be minimal and hairiness and pigmentation obvious. Characteristically it is a unilateral lesion of the shoulder in males but it may affect other sites, be multiple and bilateral, and be found in women and Negroes. Histological examination may show no epidermal thickening. Nevus cells are not seen in the dermis.