Autoimmune pancreatitis--recent advances

Autoimmune pancreatitis (AIP) is recognized as a distinct clinical entity, identified as a chronic inflammatory process of the pancreas in which the autoimmune mechanism is involved. Clinically and histologically, AIP has two subsets: type 1--lymphoplasmatic sclerosing pancreatitis with abundant infiltration of the pancreas and other affected organs with immunoglobulin G4-positive plasma cells, and type 2--duct centric fibrosis, characterized by granulocyte epithelial lesions in the pancreas without systemic involvement. In the diagnosis of AIP, two diagnostic criterions are used--the HISORt criteria and Asian Diagnostic Criteria. In the differential diagnosis, the pancreatic cancer must be excluded by endosonographically guided pancreatic biopsy. Typical signs of AIP are concomitant disorders in other organs (kidney, liver, biliary tract, salivary glands, colon, retroperitoneum, prostate). Novel clinicopathological entity was proposed as an 'IgG4-related sclerosing disease' (IgG4-RSC). Extensive IgG4-positive plasma cells and T lymphocyte infiltration is a common characteristics of this disease. Recently, IgG4-RSC syndrome was extended to a new entity, characterized by IgG4 hypergammaglobulinemia and IgG4-positive plasma cell infiltration, this being considered an expression of a lymphoproliferative disease, 'IgG4-positive multiorgan lymphoproliferative syndrome'. This syndrome includes Mikulicz's disease, mediastinal fibrosis, autoimmune hypophysitis, and inflammatory pseudotumor--lung, liver, breast. In the therapy of AIP, steroids constitute first-choice treatment. High response to the corticosteroid therapy is an important diagnostic criterion. In the literature, there are no case-control studies that determine if AIP predisposes to pancreatic cancer. Undoubtedly, AIP is currently a hot topic in pancreatology.