Dermal melanocytosis: a clinical spectrum.

While most dermal melanocytoses are congenital or have an onset in early childhood, there is a group which is clearly acquired, with an onset in adult life. While the Mongolian spot typically disappears in childhood, other dermal melanocytoses persist for life. A brief review of the clinical spectrum of the dermal melanocytoses is undertaken and three illustrative cases are described: a case of congenital naevus of Ota, a case of acquired bilateral naevus of Ota-like macules, and an unusual case of a congenital dermal melanocytotic lesion on the left had which began to spread in adulthood. The possibilities regarding the pathogenesis of this intriguing group of disorders are considered.