Malignant neoplasm of intrahepatic bile ducts

**Definition:** A carcinoma that arises from the intrahepatic bile duct epithelium in any site of the intrahepatic biliary tree. Grossly, the malignant lesions are solid, nodular, and grayish. Morphologically, the vast majority of cases are adenocarcinomas. Early detection is difficult and the prognosis is generally poor.