Circumscribed dermal melanoses. Classification and histologic features

Dermal melanosis is caused by deposition of melanin in melanophages or by free melanin in the dermis or in dermal melanocytes. Circumscribed dermal melanoses can be congenital or acquired and at times are nevoid in distribution. Bilateral nevus of Ota-like lesions and blue macules recently have been described in association with progressive systemic sclerosis. Macular amyloidosis and friction melanosis are also acquired dermal melanoses. It is important to distinguish dermal melanoses caused by the presence of melanocytes in the dermis from those produced by the presence of melanin free within the dermis. Clinically, the two different processes may have very similar appearances. Treatments for circumscribed dermal melanoses include cosmetics, cryotherapy, dermabrasion, or, rarely, skin grafts.