Merkel Cell Carcinoma

**Semantic type:** Neoplastic Process

**Definition:** A rare aggressive neuroendocrine carcinoma that usually arises from the skin. Rarely, it arises from extracutaneous sites, including the oral cavity, salivary glands, breast, vulva, and vaginal wall. The tumor is composed of small round cells with scanty cytoplasm. Merkel cell polyomavirus is implicated in the majority of cases.

**Synonyms:** - MCC - Merkel Cell Cancer - Merkel cell cancer - Merkel cell carcinoma - Merkel cell carcinoma - Merkel cell carcinoma, unspecified - Merkel cell tumor - Merkel cell tumor