Pigmented epithelioid melanocytoma: Report of a case and review of 173 cases in the literature

Pigmented epithelioid melanocytoma (PEM), or animal-type melanoma, is an unusual variant of melanoma which has been reported to have indolent behavior and a relatively good prognosis. We report a 12-year-old girl with PEM on the third finger web of her right hand. Histopathologically, it was composed of heavily pigmented dermal epithelioid and spindled melanocytic tumor cells. A sentinel lymph node biopsy was negative, and no recurrence was noted 1 year later. We reviewed 173 previously published cases of PEM or so-called animal-type melanoma in the literature. Among the 173 cases and our case, extremities were the most common sites of occurrence (52/129, 40.3%), and most of the depth of invasions were Clark level IV and V [76/114 (66.7%) and 33/114 (28.9%), respectively]. Lymph nodes metastasis was noted in 39/89 (43.8%) of the cases being investigated. Only two cases died of the disease with visceral metastasis. Thus, a more advanced level of invasion and the presence of lymph node metastasis did not imply a definitely malignant clinical course, because spreading beyond lymph nodes was rare (5/174, 2.9%). However, long-term follow-up with more cases and further research are needed to fully delineate the true biological nature of this pigmented melanocytic tumor. Copyright (C) 2012, Taiwanese Dermatological Association. Published by Elsevier Taiwan LLC. All rights reserved.