Cholangiocarcinoma is a carcinoma arising in any part of the biliary tree from the small intrahepatic bile ducts to the ampulla of Vater at the distal end of the common bile duct. More than 90% of cholangiocarcinomas are ductal adenocarcinomas and the remainder are squamous cell tumours.[1]
Most commonly, they occur in the perihilar region (classical Klatskin's tumour) near the bifurcation of right and left hepatic ducts.
Tumours occurring between the upper border of the pancreas and ampulla of Vater are the next most common and are classified as distal extrahepatic tumours.
Can also occur (least commonly) as an intrahepatic tumour.