Overview of types 1 and 2

Autoimmune pancreatitis (AIP) is a recently defined new disease entity with pathogenesis possibly related to autoimmunity. Originally it was characterized by impressive imaging of the pancreas, such as diffuse swelling with main pancreatic duct narrowing, serologically an elevation of serum IgG4 and an appearance of various autoantibodies, pathologically lymphoplasmacytic sclerosing pancreatitis (LPSP), and an association of various extrapancreatic organ involvement representatively such as sclerosing cholangitis, sialadenitis, retroperitoneal fibrosis, and so on. This type AIP is recently considered to be a pancreatic manifestation of the integrated concept of IgG4-related disease. On the other hand, another type of autoimmune-related pancreatitis was proposed, which is defined pathologically by idiopathic duct-centric chronic pancreatitis (IDCP) or granulocytic epithelial lesion (GEL). Recent studies have shown the clinical features of this type being quite different from the former type, suggesting distinct category. World experts agreed that they are different types of autoimmune pancreatitis and should be given nomenclatures of type 1 AIP for the former and type 2 AIP for the latter. Based on this Honolulu consensus, the International Consensus Diagnostic Criteria (ICDC) for AIP was compiled based on the consensus of world experts after a hot discussion in the symposium at the 14th IAP and 41st JPS joint conference in Fukuoka in 2010. Now we are ready to study and discuss globally on the same ground by the ICDC the pathogenesis, the clinical features, and the best treatment for AIP.