Biliary Tract Cancer

The biliary tract comprises of gallbladder and intra and extrahepatic biliary tree. Bile is directed through these ducts to the second part of duodenum at major duodenal papilla. The epithelium of the biliary tract is lined with cells called cholangiocytes. Carcinoma of the biliary tract arises from the malignant transformation of the epithelium of the bile ducts which is made up of these cholangiocytes, and is categorized on the basis of its anatomical location as; 1) Intrahepatic cholangiocarcinoma 2) Extrahepatic cholangiocarcinoma, which includes; perihilar tumor also known as Klatskin tumor (originating from the epithelium of the bile duct at the junction of right and left hepatic ducts with the cystic duct where it forms the common bile duct) and distal cholangiocarcinoma outspreading to encompass the gallbladder, ampulla of Vater and pancreatic biliary ducts. Although both intrahepatic and extrahepatic cholangiocarcinoma arises from the same epithelium of the bile duct, the pathogenesis and clinical outcomes of extrahepatic cholangiocarcinoma differs from that of intrahepatic cholangiocarcinoma on the basis of different anatomical location. Cholangiocarcinoma is considered as one of the rare but most aggressive tumors with a very poor prognosis because mostly, it is advanced and unresectable by the time it is diagnosed. Late presentation of the tumor in many cases has already caused the extensive involvement of the blood vessels and the regional lymph nodes that curative surgical resection becomes a challenge. Although rare, it represents the second most common type of primary liver malignancy following hepatocellular carcinoma.