These are benign flat, raised, or pedunculated lesions, varying in colour from yellow to dark brown. They are more usual on the trunk and increase in incidence from 40 years onwards. There may be a familial tendency for widespread forms. They are not infective.
Histological examination reveals that these lesions are a localised proliferation of the basal layer of the epidermis. Often there is hyperkeratosis in the surface crypts. These lesions may be known as basal cell papillomas because of their cells of origin but are not neoplastic and are not related to basal cell carcinomas.
Treatment is rarely necessary. If required, superficial cryotherapy is usually adequate.
Last reviewed 01/2018