Synchronous onset of multiple cutaneous neuroendocrine (Merkel cell) carcinomas localized to the scalp.

Merkel cell carcinoma (MCC) is a rare aggressive neoplasm that typically presents as a solitary nodule or plaque on sun-exposed skin of the elderly. Although multiple MCC have been described, they are rare, and metastases must be excluded. We report a case of a 59-year-old white male who presented with abrupt onset of multiple small bluish papules on his frontal scalp. On low power, the tumor had the overall histological silhouette of a nodular basal cell carcinoma. However, because of the lack of an epithelial connection and the cell's cytomorphological features, a MCC was considered and was subsequently confirmed using immunohistochemical stains. The MCC described in this report is unusual in that it presented as multiple cutaneous lesions that arose synchronously, along with micrometastases to sentinel lymph nodes.