Metachronic development of cholangiocarcinoma during treatment for IgG4-related sclerosing cholangitis.

We report a case of obstructive jaundice due to recurrent distal biliary stricture during 3 years of treatment for immunoglobulin G4 (IgG4)-related sclerosing cholangitis (IgG4-SC) associated with autoimmune pancreatitis. Although a relapse of IgG4-SC was initially suspected, imaging findings, laboratory tests, and histopathological examinations led to the diagnosis of metachronous cholangiocarcinoma. The patient underwent pancreaticoduodenectomy, and no cancer recurrence was noted 6 months postoperatively. Distal cholangiocarcinoma and IgG4-SC remission were observed in the resected specimen. In patients with recurrent biliary strictures during IgG4-SC treatment, comprehensive evaluations are essential because of the risk of disease relapse and development of metachronous cholangiocarcinoma.