Review of diagnostic criteria for autoimmune pancreatitis; for establishment of international criteria

Along with worldwide expansion of the disease concept of autoimmune pancreatitis (AIP), the necessity of international diagnostic criteria for the disease is increasing. Since the first diagnostic criteria for AIP by the Japan Pancreas Society was proposed in 2002, certain groups in several countries have reported criteria for AIP. We reviewed the criteria proposed to date. Among three systematic criteria from Japan, the Mayo Clinic and Korea, there is no fundamental difference in the three major diagnostic categories: findings on pancreatic imaging, laboratory and histological studies. Notable differences are that typical imaging findings are essential for the diagnosis in Japanese and Korean criteria, but not in the Mayo criteria, while, the Mayo criteria emphasize the histological findings as a gold standard for the diagnosis. The critical differences between the Japanese and the other two criteria are the use of the diagnostic factors "other organ involvement" and "steroid responsiveness." Employment of these factors in clinical diagnostic criteria for general physicians possibly confuses the disease concept and definitely increases the risk for treating patients with pancreatic or biliary malignancies with steroids. Even if the sensitivity of criteria goes down, their use might be limited to certain kinds of specific criteria, such as that for epidemiological study, patient selection for research purposes, or use in expert hospitals. The disease entity of AIP postulated in Europe includes two histological types of pancreatitis with different clinical phenotypes, suggesting two syndromic spectra of autoimmune-related chronic pancreatitis.