Cholangiocarcinoma (CCA) is an epithelial neoplasm that spreads in the biliary tract / biliary tract mucosa and has histological characteristics of a differentiation typical of cholangiocytes. It can occur both inside (intrahepatic cholangiocarcinoma, rare) and outside the liver (extrahepatic cholangiocarcinoma, more common form).

As a rare disease, it affects only about 3% of all cancers in the digestive tract worldwide, yet it is the second most common tumor of the liver.

The etiology is unknown and most cases of CCA are sporadic. Risk factors include primary sclerosing cholangitis, secondary sclerosing cholangitis, chronic typhoid infection, parasitic infections, thorotrast exposure (X-ray contrast medium), and choledochal cysts; all of these factors cause chronic inflammation of the biliary tract.

Most CCA occur sporadically and with no obvious risk factor after the age of 50. In Southeast Asia, the region with the highest incidence of CCA, the most important risk factor is biliary infestation by liver fluke. Primary sclerosing cholangitis is a particular risk in the western world. An estimated 5-10% of patients develop CCA during the course of the disease.

Cholangiocarcinoma is rarely discovered in time and is usually incurable, as a diagnosis is often only made at a very advanced stage when surgical treatment is no longer possible.