The importance of IgG4 screening in patients diagnosed with primary sclerosing cholangitis in the past: A case rediagnosed as IgG4-SC after 10 years.

Rationale: While primary sclerosing cholangitis (PSC) has been recognized for decades, immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) has been correctly diagnosed only in recent years. PSC and IgG4-SC show similar clinical symptoms, serologic markers, and imaging results, but the treatment strategies and prognosis of patients differ.