Pediatric pigmented epithelioid melanocytoma of the scalp with NKTR3 gene rearrangement

A 4 year-old African American female presented to our clinic with a 2-month history of a growing nodule on her right parietal scalp. Clinical examination revealed an ; 3 · 3 cm skin colored subcutaneous nodule with a very small focus of superficial pigmentation. A 4 mm punch biopsy from within the nodule was obtained for histopathological analysis. On gross exam the dermis and subcutis appeared homogenously black. Microscopic analysis revealed nodular aggregations of heavily melanized epithelioid melanocytes throughout the dermis and subcutis with a mitotic rate of ; 1 per mm2. Cytologically the cells were medium-sized and demonstrated modestly pleomorphic vesicular nuclei with prominent nucleoli. The neoplasm was sent for array CGH testing and was found to have chromosomal gains and losses in 15q and gains in 17q, consistent with borderline lesion without characteristic anomalies seen in melanoma. Additionally, a breakpoint was detected within the NKTR3 gene suggestive of a rearrangement. Complete re-excision of the entire neoplasm revealed identical morphological findings. Overall, the features in this case were consistent with a diagnosis pigmented epithelioid melanocytoma (PEM). The presence of an NKTR3 rearrangement in this case adds to the potential characteristic genomic alterations that have been recently described in this entity