To analyze the computed tomography (CT) characteristics of hepatocellular carcinoma (HCC) with hilar bile duct tumor thrombus (HBDTT) and to investigate the differential imaging features of hilar cholangiocarcinoma (hilar CC).

From January 2013 to December 2018, fourty-two cases with pathologically proved HCC with HBDTT (HBDTT group) and fifty-one cases of hilar CCs (hilar CC group) from the First Affiliated Hospital of Sun Yat-sen University and Xinhui Traditional Chinese Medicine Hospital were retrospectively collected. The clinical features and CT findings between the two groups were compared and analyzed.

Compared with hilar CC group, the proportion of male, hepatitis B history and upper abdominal pain were higher in HBDTT group, and increased alpha-fetoprotein (AFP) levels were common. However, there were more patients with elevated CA19-9 and carcinoembryonic antigen (CEA) in hilar CC group (P<0.05). On CT imaging characteristics, the presence of both parenchymal lesion with intraductal lesion, washout during the portal venous phase, thickened bile duct wall , intrahepatic vascular embolus, splenomegaly had significant differences between the two groups (P<0.001), all of these five characteristics showed high specificity (82.4%-98.0%), and the first three showed higher sensitivity (100.0%, 92.9%, 85.7%).

CT can be used for accurate differential diagnosis of HCC with HBDTT and hilar CC. The lesion involved both the liver parenchyma and hilar bile duct, washout during portal venous phase and without thickened bile duct wall are characteristic signs of HCC with HBDTT, which are important for the identification of HCC with HBDTT and hilar CC, when combined with hepatitis B virus infection and AFP levels.