Immunoglobulin G4-related sclerosing cholangitis mimicking cholangiocarcinoma: a case report and literature review.

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a novel clinical disease that is characterized by elevated serum IgG4 concentrations and tumefaction or tissue infiltrated by IgG4+ plasma cells. The clinical manifestations of IgG4-RD depend on the type of tissues affected. IgG4-related sclerosing cholangitis is a type of IgG4-RD. We report a patient who initially visited a local hospital with a 5-month history of jaundice. He was found to have a mass in the upper part of the common bile duct that mimicked cholangiocarcinoma. He underwent surgery in our hospital and was later diagnosed with IgG4-related sclerosing cholangitis. We administered prednisolone 40 mg once a day for treatment. Taking into account the possible side effects of moderate-dose hormone therapy, we also administered teprenone, potassium chloride, and calcium carbonate. The patient did not have any recurrence of symptoms or adverse drug reactions during follow-up.