IgG4-related sclerosing cholangitis- A great mimicker.

IgG4-related disease (IgG4 RD) is a multisystem disorder characterized by tumefactive (mass forming) lesions, storiform fibrosis, and IgG4-positive plasma cell infiltration. IgG4 sclerosing cholangitis (IgG4 SC) is the biliary manifestation of IgG4 RD, often in association with autoimmune pancreatitis (AIP). Here, we report two patients with IgG4-related cholangitis mimicking primary sclerosing cholangitis.