In 1961, Sarles et al.1 asked the following question regarding the particular cases of pancreatitis with hypergammaglobulinemia: “Chronic inflammatory sclerosis of the pancreas—an autoimmune pancreatic disease?” As similar cases were rarely observed, a relationship between such pancreatitis and autoimmunity was viewed skeptically during the following several decades. In 1992, Toki et al.2 have reported 4 cases with unusual diffuse irregular narrowing of the main pancreatic duct and diffuse enlargement of the entire pancreas due to lymphocyte infiltration. In 1995, Japanese investigators3 firstly proposed a concept of “autoimmune pancreatitis (AIP)”, in which the patients showed diffusely enlarged pancreas, narrowing pancreatogram, increased serum IgG, presence of autoantibodies, fibrotic changes with lymphocytic infiltration and steroidal efficacy. Thereafter, many AIP cases have been reported from Japan, and AIP has been accepted as a new clinical entity.4,5 The histopathological findings of AIP show massive infiltration of lymphoplasmacytes with fibrosis, which is consistent with lymphoplasmacytic sclerosing pancreatitis (LPSP).6 Many Japanese investigators have paid great attention to AIP, especially with regard to its unique pancreatic images,2 IgG4,7 disease-associated autoantibodies,8 extrapancreatic lesions,6,9–14 and steroidal efficacy.14,15 Currently in Japan, diagnosis of AIP is based on the “diagnostic criteria 2002 of autoimmune pancreatitis”16 proposed by the Japan Pancreas Society. However, the accumulation of many AIP cases shows that the concept of AIP has changed slightly to include extrapancreatic lesions and associated disorders, which suggests that the current diagnostic criteria are becoming inadequate. In 2003, the Research Committee of Intractable Diseases of the Pancreas, supported by the Japanese Ministry of Health, Labour and Welfare (Chairman, M. Otsuki), began to review the current diagnostic criteria in light of recently acquired information and knowledge. The team organized a working group (WG), consisting of the team members and researchers specializing in autoimmune pancreatitis, to develop a proposal for the revision of the current diagnostic criteria. On 7 October 2005 and 22 April 2006, the Research Committee of Intractable Diseases of the Pancreas and the Japan Pancreas Society jointly held open forums to discuss the proposed amendments. This report describes the background of the proposed amendments and the final proposal for the revised version of the clinical diagnostic criteria of AIP.
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