Primary Cutaneous Neuroendocrine Carcinoma (Merkel Cell Tumor)

• DOI: 10.1097/00000372-199002000-00002
• Publication Date: 2006-11-10T09:44:13Z
• Authors: Peter J. Heenan; Judith M. Cole; Dominic V. Spagnolo
• Keywords: Merkel cell; Enolase; Pleomorphism (cytology); Neuroendocrine differentiation; Anaplastic carcinoma; Large cell

We report 18 cases of primary cutaneous neuroendocrine carcinoma (CNEC, Merkel cell tumor) that occurred mainly in the sun-exposed skin elderly patients as dermal and subcutaneous masses generally monomorphic cells with foci pronounced pleomorphism. All showed immunoreactivity for neuron-specific enolase (NSE), whereas 16 them another marker, protein gene product 9.5 (PGP 9.5). Positivity PGP was more intense sharply localized to tumor than staining NSE. Immunoreactivity keratins detected by AE1/AE3 CAM 5.2 monoclonal antibodies found 15 cases, respectively, prominent paranuclear globular staining. One case stained positively S-100 protein; all were negative leukocyte common antigen (LCA). Typical ultrastructural features differentiation noted 14 tumors examined. Morphological immunohistochemical similarities between these neoplasms pulmonary small-cell anaplastic carcinoma, now thought be bronchial basal origin, suggest CNEC are also derived from epithelium. In addition, their location suggests this epithelium is likely adnexal rather epidermal.