doi: 10.1111/j.1346-8138.2007.00245.x Journal of Dermatology 2007; 34: 178 –182 178 © 2007 Japanese Dermatological Association Blackwell Publishing Asia CASE REPORT Clinically distinct form of acquired dermal melanocytosis with review of published work Catherine HARRISON-BALESTRA, 1 Dijana GUGIC, 2 Vladimir VINCEK 2 1 Department of Dermatology and Cutaneous Surgery, 2 Department of Pathology, School of Medicine, University of Miami, Miami, Florida, USA ABSTRACT Dermal melanocytosis is most commonly found in the skin of Asians and other darkly pigmented people. It is histologically characterized by the presence of dermal melanocytes, with or without presence of dermal melano- phages. Mongolian spot, nevus of Ito, nevus of Ota, nevus of Hori, and blue nevus are most common and repre- sent distinct types of dermal melanocytosis. Other clinical patterns of acquired dermal melanocytosis have also been described. Herein, we report a unique case of acquired dermal melanocytosis diffusely affecting the entire back of a 50-year old African-American male and also review and discuss various patterns of unusual acquired dermal melanocytosis. Key words: acquired dermal melanocytosis, hyperpigmentation. INTRODUCTION Dermal melanocytosis includes several benign pigmented lesions that are histologically charac- terized by the presence of melanocytes in the dermis. 1 Clinically, they are characteristically gray or blue-gray in color as a consequence of the color transmission of black melanin pigment through the dermis. Some of them, like Mongolian spot, nevus of Ito or nevus of Ota, are present at birth and are more common in Asian subjects. 2–4 Others, like nevus of Hori, Sun’s nevus or blue nevus appear in childhood or later in life. 5–7 There are rare reports of acquired dermal melanocytosis in adults that do not belong to any of these common forms, and are usually associated with some other pre- existent cause. 8 We herein report a case of adult acquired dermal melanocytosis with a unique clinical presentation. We also review and discuss various patterns of unusual acquired dermal melanocytosis. CASE REPORT We are reporting an otherwise healthy, African- American, male patient of 50 years old, with a 20 year long history of blue-gray, non-palpable patches, darker than the surrounding skin, diffusely and symmetrically involving his entire back (Fig. 1). Other parts of his body, including the face, were not involved. There was no associated hypertrichosis. These patches were asymptomatic and the patient denied any prior inflammation to the area. He also denied using any medications or metals that could possibly alter skin pigmentation. There was no family history of similar skin problems. Biopsy showed multiple spindle-shaped dendritic melanocytes in the dermis (Fig. 2). The melanocytes, staining positive with S100 antibodies (Fig. 3a), were singly disposed and their cellularity was sparse. They contained brown melanin pigment staining with Fontana–Masson stain for melanin (Fig. 3b). Immunoperoxidase staining with CD68 antibody Correspondence: Vladimir Vincek, MD, PhD, University of Miami/Jackson Memorial Hospital, Department of Pathology, Holtz Center, Room 2042, 1161 NW 12 Avenue, Miami, FL 33136, USA. Email: vvincek@med.miami.edu Received 11 May 2006; accepted 24 August 2006.