Cholangiocarcinoma arising near or at the confluence of the right and left hepatic ducts (COMMON HEPATIC DUCT). These tumors are generally small, sharply localized, and seldom metastasizing. The disease is EFO_1001005 (Klatskin's tumor). Also known as: Klatskin tumor, Klatskin's Tumor, Klatskin's tumor (disorder), Klatskin's tumor (morphologic abnormality), Perihilar extrahepatic bile duct carcinoma, hilar cholangiocarcinoma.