Cutaneous epithelioid melanocytic neurofibroma arising in a patient with neurofibromatosis-1.
Novoa, Roberto A. 1; Kovarik, Carrie L. 1; Low, David W. 2; Argenyi, Zsolt 3
[Report]
Journal of Cutaneous Pathology.
41(5):457-461, May 2014.
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: Tumors expressing both melanocytic and neural features can pose a diagnostic challenge to the dermatopathologist and provoke questions regarding their lineage. We report a case of a tumor arising on the right cheek of a 9-year-old boy with neurofibromatosis type 1 (NF-1). This neoplasm featured nests of non-pigmented epithelioid cells arising within a neurofibroma. The entire tumor stained strongly with S100, whereas the epithelioid population stained with MART-1, HMB-45 and MiTF. The neoplasm shows only scattered Ki-67 positivity. This tumor represents a neurofibroma with portions that have undergone melanocytic differentiation (melanocytic neurofibroma). This exceedingly rare tumor represents a distinct entity from neurotized melanocytic nevi, combined melanocytic nevi or pigmented neurofibromas and provides further evidence that melanocytes arise indirectly from ventromedial neural crest-derived Schwann cell precursors.
(C) 2014 John Wiley & Sons, Ltd