Immunoglobulin G4-associated sclerosing cholangitis mimicking cholangiocarcinoma.

Immunoglobulin G4-related lymphoplasmacytic sclerosing disease is an emerging disease. Recently, it has been shown to be responsible for autoimmune pancreatitis-induced strictures of the bile duct mimicking cholangiocarcinoma. Making a diagnosis of immunoglobulin G4-associated sclerosing cholangitis requires a high index of suspicion. The differential diagnoses include primary sclerosing cholangitis, cholangiocarcinoma, and pancreatic cancer. The preoperative diagnosis is likely to be missed due to the lack of specific symptoms; a clinical presentation that may mimic other disorders, especially malignant biliary strictures; and the lack of specific imaging features. This article reports on a 51-year-old man with immunoglobulin G4-associated sclerosing cholangitis without autoimmune pancreatitis. He underwent resection of his extrahepatic bile duct with a hepaticojejunostomy. The diagnosis was confirmed after a histopathological examination. This case highlights the obstacles to making a preoperative diagnosis of immunoglobulin G4-associated sclerosing cholangitis.