[Autoimmune pancreatitis].

Autoimmune pancreatitis is a unique form of chronic pancreatitis characterized by high serum IgG4 concentrations and abundant IgG4-bearing plasma cell infiltration in the pancreatic lesion. This disease is based on the clinical features of histological evidence of lymphoplasmacytic sclerosing pancreatitis and fibrosis, irregular narrowing of the pancreatic duct, and a favorable response to glucocorticoid treatment. The initial prednisone dosage is 30 to 40 mg/day, tapered in 5-mg reductions every one to two weeks. Other features of this disease involve a variety of extra-pancreatic complications seen in sclerosing cholangitis, Mikulicz disease, as manifested by lachrymal and salivary gland swellings, hilar lymphadenopathy, and retroperitoneal fibrosis. Some of these extra-pancreatic lesions show pathological findings similar to those of pancreatic lesions, including infiltration by abundant IgG4-bearing plasma cells.