[IgG4-related sclerosing disease, including its relation to carcinogenesis].

IgG4-related sclerosing disease is a systemic disease histologically characterized by extensive T lymphocytes and IgG4-positive plasma cell infiltration of various organs. Major clinical manifestations are apparent in the pancreas (autoimmune pancreatitis), bile duct (sclerosing cholangitis), gallbladder (sclerosing cholecystitis), salivary gland (sclerosing sialadenitis), and retroperitoneum (retroperitoneal fibrosis), in which tissue fibrosis with obliterative phlebitis is pathologically induced. Autoimmune pancreatitis is a pancreatic lesion and its extrapancreatic lesions are organs reflecting an IgG4-related sclerosing disease. In some cases, only one or two organs are clinically involved, while in others three or four organs are affected. The disease occurs predominantly in elderly males, is frequently associated with lymphadenopathy, and responds well to steroid therapy. Since malignant tumors are frequently suspected on initial presentation, IgG4-related sclerosing disease should be considered in the differential diagnosis to avoid unnecessary surgery. Some cases of autoimmune pancreatitis were reportedly associated with pancreatic cancer. Although no relationship between the two diseases is known, we showed frequent and significant K-ras mutations in the pancreas, the bile duct, and the gallbladder in autoimmune pancreatitis.