Cancers can occur in any part of the bile duct. The location of the primary tumor (inside or outside the liver) and the kind of cell involved are what determine the particular type of bile duct cancer.
Extrahepatic bile duct cancer develops in the ducts outside of the liver. Most bile duct cancers are extrahepatic, including:
- Adenocarcinomas, the most common type of extrahepatic bile duct cancer, form in the cells of the mucous gland lining the inside of the bile duct. Adenocarcinomas account for about 95 percent of all bile duct cancers. Bile duct adenocarcinoma is also called cholangiocarcinoma.
- Hilar (or perihilar) bile duct cancers, also called Klatskin tumors, form where hepatic duct branches leave the liver. About two-thirds of all bile duct cancers are hilar or perihilar in origin.
- Distal bile duct cancer occurs near the small intestine, at the opposite end of the duct from perihilar cancer. About one-fourth of all bile duct cancers begin at this location.
Intrahepatic bile duct cancer begins in the liver, in the smaller duct branches. Only about 5 percent to 10 percent of all bile duct cancers are intrahepatic. Intrahepatic bile duct cancers are sometimes misdiagnosed as liver cancer, and both are typically treated the same way.
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