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. 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.