[IgG4-related sclerosing disease].

IgG4-related sclerosing disease (IgG4-RSD) is a systemic one in which IgG4-positive plasma cells and T lymphocytes extensively infiltrate various organs. The clinical manifestations of the disease include autoimmune pancreatitis, sclerosing cholangitis, cholecystitis, sialodenitis, retroperitoneal fibrosis, tubulointestitial nephritis, interstitial pneumonia, prostatitis, inflammatory pseudotumors and lymphadenopathy, all related with significantly elevated serum IgG4 levels. Tissue fibrosis with obliterative phlebitis of the affected organs is pathologically induced. The disease occurs predominantly in elderly men and responds well to steroid therapy. Since malignant tumors are frequently suspected on initial presentation, IgG4-RSD should be considered in the differential diagnosis to avoid unnecessary surgery.