Title: CLINICAL DIAGNOSTIC CRITERIA OF AUTOIMMUNE PANCREATITIS 2006
Abstract: : Autoimmune pancreatitis (AIP) is a characteristic pancreatitis in which autoimmunity is a suspected pathogenic mechanism, showing the diffuse enlargement of the pancreas, the narrowing of the main pancreatic duct, increased levels of γ-globulin and IgG, and the presence of autoantibodies. Patients with AIP often experience epigastric discomfort, obstructive jaundice due to bile duct stricture, and diabetes mellitus. Steroid therapy is quite effective for these clinical and imaging features. Japan Pancreas Society first proposed a diagnostic criteria of AIP in 2002 (Suizo 2002; pp 17:587). Currently, it has been observed that AIP associates sclerosing cholangitis, sclerosing sialadenitis, and retroperitoneal fibrosis, based on the accumulation of many AIP patients, suggesting that AIP may be a systemic disease. Thus, the concept of AIP has changed to include extra-pancreatic lesions and associated disorders, and the diagnostic criteria 2002 are becoming inadequate. The Research Committee of Intractable Diseases of the Pancreas supported by the Japanese Ministry of Health, Labor and Welfare, and the Japan Pancreas Society revised and proposed new clinical diagnostic criteria of AIP 2006, after several forums to discuss the revised criteria. The most important problem in diagnosing AIP is how to distinguish it from pancreatic or biliary cancer. The clinical criteria are based on the minimum consensus features of AIP in order to avoid the misdiagnosis of malignancy as far as possible, but not to pick up suspicious cases of AIP. The detail of the revised criteria has been published also in J Gastroenterology (Okazaki, et al. 2006; pp 40:626-31). Clinical Diagnostic Criteria of AIP. 1. Diffuse or segmental narrowing of themain pancreatic duct with irregular wall and diffuse or localized enlargement of the pancreas by imaging studies, such as abdominal ultrasonography, computed tomography, and magnetic resonance imaging. 2. High serum γ-globulin, IgG, or IgG4, or the presence of autoantibodies, such as antinuclear antibodies and rheumatoid factor. 3. Marked interlobular fibrosis and prominent infiltration oflymphocytes and plasma cells in the periductal area, occasionally with lymphoid follicles in the pancreas. Diagnosis of AIP is established when criterion 1, together with criterion 2 and/or 3, are fulfilled. However, it is necessary to exclude malignant diseases such as pancreatic or biliary cancers.