MSH: A malignant tumor arising from the intrahepatic bile duct epithelium. It is composed of ducts lined by cuboidal or columnar cells that do not contain bile, with abundant stroma. (From Holland et al., Cancer Medicine, 3d ed, p1455; Stedman, 25th ed),NCI: A rare type of cancer that develops in cells that line the bile ducts in the liver. Cancer that forms where the right and left ducts meet is called Klatskin tumor.,NCI: A malignant neoplasm arising from/comprising cells resembling those of bile ducts.,NCI: A carcinoma that arises from the intrahepatic biliary tree (intrahepatic cholangiocarcinoma) or from the junction, or adjacent to the junction, of the right and left hepatic ducts (hilar cholangiocarcinoma). Grossly, the malignant lesions are solid, nodular, and grayish. Morphologically, the vast majority of cases are adenocarcinomas. Signs and symptoms include malaise, weight loss, right upper quadrant abdominal pain, and night sweats. Early detection is difficult and the prognosis is generally poor.