A Case of Obstructive Jaundice due to Bile Duct Tumor Thrombus of Hepatocellular Carcinoma Diagnosed by Peroral Cholangioscopy.

While hepatocellular carcinoma (HCC) often invades the portal or hepatic vein to form tumor thrombus, tumor thrombus in the bile duct is rare. In such cases, differentiation from intrahepatic cholangiocarcinoma is difficult, and the tumor often appears as a smooth, yellowish-white, polypoid mass within the bile duct lumen. We report herein a case of obstructive jaundice due to bile duct tumor thrombus of HCC diagnosed by peroral cholangioscopy (POCS). A 64-year-old man presented with epigastralgia and jaundice. Contrast-enhanced computed tomography revealed an irregular mass with hypoenhancement in liver segment S8, along with dilatation of the right intrahepatic bile duct due to the invading tumor. The hepatic mass was poorly visualized on ultrasound, making percutaneous liver tumor biopsy difficult. POCS was performed after endoscopic retrograde cholangiopancreatography for biopsy of the intrahepatic bile duct tumor thrombus. POCS clearly revealed a smooth, yellowish-white, polypoid tumor in the right intrahepatic bile duct, and a biopsy of the tumor was performed under POCS. Based on the pathological findings, HCC was diagnosed, and chemotherapy with atezolizumab and bevacizumab was initiated.