label: Merkel Cell Carcinoma
label_lc: merkel cell carcinoma
description: "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."