Congenital segmental dermal melanocytosis in an adult

• Background.— Dermal melanocytosis is characterized by the presence of melanocytes in the dermis. There are several morphologic forms, such as the blue nevus, the mongolian spot, the nevus of Ota, and the nevus of Ito. In this article, we report an unusual case of dermal melanocytosis. Observations.— A 28-year-old white woman was referred to us, as she had an extensive, speckled gray-blue pigmentation on the right aspect of her trunk that was in a segmental pattern. The lesion had been present at birth. Histologic and ultrastructural examinations revealed sparse, elongated dermal melanocytes. Conclusions.— We comment on the differential diagnosis with classic recognized forms of dermal melanocytosis. We also review other isolated cases of unusual dermal melanocytosis. This is a distinct case, clinically different from previously reported cases in the literature; we propose the term "congenitalsegmental dermal melanocytosis" to name this case. ( Arch Dermatol. 1992;128:521-525)