A Case of Biliary Cast Syndrome with Cholangiocarcinoma-like Lesion in a Patient with No History of Liver Transplantation.

: Biliary cast syndrome, which was first reported in 1975, is a rare disease that occurs after liver transplantation. The incidence is even lower in patients who have not undergone liver transplantation. This study reports a rare case of biliary cast syndrome with cholangiocarcinoma-like lesions in a patient who did not undergo liver transplantation. Herein, we report a case of a 69-year-old man with right upper quadrant pain and elevated levels of alkaline phosphatase and gamma-glutamyl transferase, who had a history of total gastrectomy for gastric cancer and laparoscopic cholecystectomy for acute cholecystitis. Computed tomography (CT) revealed longitudinal bile stones in the extrahepatic and intrahepatic bile ducts and abrupt narrowing of the left main bile duct accompanied by a narrowing of the upstream bile duct in the left lobe of the liver. Based on the CT findings, the removal of the bile stones in the bile duct and additional examinations of the suspected cholangiocarcinoma were performed. The patient's symptoms improved, and examinations for suspected cholangiocarcinoma showed no abnormal findings, and he was discharged one month later. : The purpose of this case report is to share a rare case of Biliary Cast Syndrome (BCS) occurring without liver transplantation. Additionally, the report aims to share image findings that mimic cancer in BCS, with the goal of reducing unnecessary repetitive biopsies, minimizing patient discomfort, and decreasing unnecessary costs by aiding in the diagnosis of BCS.