<prompt> Most common site of cholangiocarcinomaDistal biliary tractHilumIntrahepatic ductMultifocal  <response>: Cholangiocarcinoma Tumors arising from bile duct epithelium. Most common type is adenocarcinoma Differentiated by anatomic site of origin: Intrahepatic 10, Hilar 65, and distal 25 MC gene mutation is K-ras p16KRAP-16 Ref: Sabiston 20th edition Pgno :1514-1518 