Nodal Merkel Cell Carcinoma with Neuroblastoma Differentiation: A Case Report and Review of the Literature

We report a case of a neuroendocrine carcinoma of the inguinal lymph node without a known identified primary site, which demonstrated the morphologic and immunophenotypic features of a Merkel cell carcinoma with neuroblastic differentiation. The neoplasm had a predominant high-grade neuroendocrine component with small cell features and a contiguous area with lobular foci of neuroblastic rosettes and fibrillary neuropil.Merkel cell carcinoma can occasionally demonstrate aberrant differentiation to other epithelial and nonepithelial cell lines, and this case is only the fourth in the available literature with neuroblastic differentiation. It is necessary to exclude a primary site of origin, but a few cases of primary neuroendocrine tumor of the lymph node have been described, with the inguinal region as the most common site of occurrence.