Intrahepatic cholangiocarcinoma Cholangiocellular carcinoma is a type of primary liver cancer that occurs in the intrahepatic bile ducts (i.e., above the first intrahepatic branch of the left and right hepatic ducts). Etiology Intrahepatic cholangiocarcinoma is a cancer of the bile duct epithelium from the merging part of the left and right hepatic ducts (hepatoportal part) to the end. It is histologically adenoid differentiated or with mucus secretion, rich in fibrous mesenchyme, and harder than hepatocellular carcinoma. According to its site of occurrence, it is classified into terminal bile duct cancer (intrahepatic cholangioma) and cholangiocarcinoma of the hilar region. Clinical manifestations Clinical symptoms vary according to the site of occurrence. Terminal cholangiocarcinoma is asymptomatic in early stage, but in late stage, there may be epigastric discomfort, liver size and weight loss, etc.; portal cholangiocarcinoma often has jaundice as the first symptom. Imaging manifestations CT manifestations: 1. Terminal cholangiocarcinoma: the plain scan shows low-density occupying lesions with irregular edges, and the density is generally uniform. In early stage, enhancement scan shows a mild ring-like enhancement at the edge of tumor, and in advanced stage, it shows a low-density ring at the edge of tumor, while the center shows a high density, and the expansion of intrahepatic bile ducts at the terminal side of tumor is also visible. Tumors below 2 cm often do not show the above enhancement features and only show mild enhancement of the whole tumor. Sometimes it is difficult to distinguish from hepatocellular carcinoma. In addition, papillary cholangiocarcinoma developing in the terminal bile duct is often diagnosed only on the basis of limited dilatation of the terminal bile duct, and should be distinguished from intrahepatic bile duct stones. 2.Cholangiocarcinoma of the porta hepatis: on plain scan, the tumor is dense to equal with the surrounding liver parenchyma, and the intrahepatic bile ducts are significantly dilated. At the early stage of enhancement, the tumor becomes hypodense, and after about 10-15 min, the center of the tumor becomes high density. This dynamic change has important diagnostic value. Only when the intramural infiltration has not yet formed extra-mural intrahepatic mass, CT enhancement only shows bile duct wall hypertrophy, which needs to be paid attention to the differential diagnosis with chronic cholangitis. However, the duct wall thickening is uneven and shows stiffness as its difference. Differential diagnosis Differentiation from hepatocellular carcinoma and liver abscess is required.