ABSTRACT
Dermal melanocytosis is characterized by the presence of ectopic melanocytes in the dermis. Dermal melanocytosis assumes several morphologic forms, including the Mongolian spot, the blue nevus, the nevus of Ota, the nevus of Ito and dermal melanocytic hamartoma. Differential diagnostic features of these dermal melanocytic lesions depend on onset, course, distribution, histologic features, uniformity of pigmentation, etc. In our case, an 18-year-old girl had asymptomatic 5x3cm sized ill-defined bluish patch on left forearm since birth. Histologic examinations revealed marked increased infiltrate of pigment cells mainly in the upper dermis in Hematoxylin & eosin stain . Fontana-Masson stain and Gp 100 stain revealed marked infiltrate of melanin-containing cells in upper dermis. We report a rare case of dermal melanocyte hamartoma.