Cutaneous epithelioid melanocytic neurofibroma arising in a patient with neurofibromatosis-1.
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.
University of Pennsylvania, Department of Dermatology, Philadelphia, PA, USA.
Roberto A
RA
Novoa
Carrie L
CL
Kovarik
David W
DW
Low
Zsolt
Z
Argenyi
D014408:Biomarkers, Tumor / Q000032:analysis; D002454:Cell Differentiation; D002648:Child; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008544:Melanocytes / Q000473:pathology*; D009456:Neurofibromatosis 1 / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*
D014408:Biomarkers, Tumor
immunohistochemistry; melanocytic lesions; neural crest