IgG4-related systemic disease, including autoimmune pancreatitis, is a multi-organ disorder characterized by elevated serum immunoglobulin G4 (IgG4) concentration and IgG4-positive plasma cell infiltration. We report a case of a 66-year-old woman with IgG4-related hearing disorder, presenting with fluctuating mixed hearing loss with middle ear effusion. The serum IgG4 level was elevated and pat...