Extrahepatic Bile Duct Small Cell Neuroendocrine Carcinoma

**Semantic type:** Neoplastic Process

**Definition:** An aggressive high-grade carcinoma with neuroendocrine differentiation that arises from the extrahepatic bile ducts and is composed of malignant small cells. The mitotic count is more than 20 per 2 mm2 and/or the Ki-67 index is more than 20%.

**Synonyms:** - Extrahepatic Bile Duct Small Cell Carcinoma - Extrahepatic Bile Duct Small Cell NEC - Oat Cell Carcinoma of Extrahepatic Bile Duct - Oat Cell Carcinoma of the Extrahepatic Bile Duct - Oat Cell Extrahepatic Bile Duct Carcinoma - Small Cell Adenocarcinoma of Extrahepatic Bile Duct - Small Cell Adenocarcinoma of the Extrahepatic Bile Duct - Small Cell Extrahepatic Bile Duct Carcinoma - Small Cell Extrahepatic Bile Duct Neuroendocrine Carcinoma