Cholangiocarcinoma: Making the diagnosis

Cholangiocarcinoma is a primary liver malignancy arising from cells forming the biliary tree (Figure 1). Although the term originally described only intrahepatic tumors, lately the term has been used to describe tumors arising from extrahepatic bile ducts as well. Perihilar tumors are also knows as Klatskin tumors, named from Klatskin's seminal article in 1965. Bismuth subclassified perihilar tumors into 4 types: (1) type I tumors, which are located in the proximal hepatic duct but not reaching the bifurcation; (2) type II tumors, which include the bifurcation; (3) type III tumors, which grow into either the right (type IIIA) or left hepatic duct (type IIIB); and (4) type IV tumors, which are defined as multicentric or involving the proximal hepatic duct and the hilus, as well as both left and right hepatic duct.