A Case of IgG4-related Sclerosing Cholangitis with intrahepatic bile duct stricture mimicking cholangiocarcinoma

The patient was 62-year-old man who was found to have an intrahepatic bile duct stricture localized in the lateral segment of the liver during a routine medical check-up. He was found to have pleural thickness, and malignant mesothelioma was suspected, because he had a history of exposure to asbestos. After extensive examination, we diagnosed cholangiocarcinoma and malignant mesothelioma. At first, we performed laparoscopic assisted left hepatectomy. Recovery was uneventful and he was discharged on postoperative day 9. Pathological diagnosis was IgG4-related sclerosing cholangitis. One month after surgery, computed tomography-guided biopsy was performed for pleural thickness. The pleural thickness was not due to malignant disease, and there were no IgG4-positive plasma cells. Therefore, we considered the pleural lesion to be related with past exposure to asbestos, and unassociated with IgG4 related disease. It is rare for localized intrahepatic bile duct stricture without intrahepatic stone to be benign, as many are malignant diseases such as cholangiocarcinoma. Extrahepatic bile duct, especially in-trapancreatic bile duct is a common site for IgG4-related sclerosing cholangitis. We present a case of IgG4-related sclerosing cholangitis with intrahepatic bile duct stricture mimicking cholangiocarcinoma, with a review of the literature.