Immunoglobulin G4-related disease with scant tissue IgG4

A 56-year-old man was admitted to our hospital for renal dysfunction and symmetrical swelling of submandibular glands. Laboratory and imaging findings were consistent with immunoglobulin G4-related disease (IgG4RD). Histological findings of the submandibular gland and the kidney were also consistent with IgG4RD. However, the patient did not have elevated serum or tissue IgG4 levels. Oral prednisolone therapy, initially 50 mg/day and gradually...