A case of IgG4-related sclerosing cholangitis overlapped with primary biliary cirrhosis.

IgG4-related sclerosing cholangitis (IgG4-SC) and primary biliary cirrhosis (PBC) can both cause liver dysfunction. While IgG4-SC is associated with IgG4-related diseases such as autoimmune pancreatitis, PBC is associated with various autoimmune diseases. However, there is only one case report of an association between IgG4-SC and PBC, and this association has not been elucidated further. The treatments for these two diseases are different, i.e., corticosteroid treatment is performed for IgG4-SC and ursodeoxycholic acid is given for PBC. We report a case of IgG4-SC overlapping with PBC in a 45-year-old man who was successfully treated by combination therapy with prednisolone and ursodeoxycholic acid.