Recent Advances in the Diagnosis and Management of Autoimmune Pancreatitis: Similarities and Differences in Japan and Korea

Two subtypes (types 1 and 2) of autoimmune pancreatitis (AIP) are currently recognized. Type 1 AIP is related to immunoglobulin G4 (lymphoplasmacytic sclerosing pancreatitis), and type 2 AIP is characterized by neutrophilic infiltration into the epithelium of the pancreatic duct (idiopathic duct-centric pancreatitis). Although type 2 AIP is sometimes observed in the United States and Europe, most cases of AIP in Japan and Korea are type 1. The international consensus diagnostic criteria for AIP were created to be applicable worldwide and to distinguish between the two types of AIP. AIP is diagnosed based on the presence of at least one of the five cardinal features (i.e., imaging, serology, other organ involvement, histology, and response to steroid therapy). Oral steroids are the standard therapy for AIP, but immunomodulatory drugs or rituximab have been successfully used for patients with relapsed AIP in the United States and Europe. Generally, the clinical manifestations and demography of AIP are similar between Japan and Korea. However, there are differences in some aspects of the disease, including the proportion of other organ involvement, the prevalence of type 2 AIP, diagnostic criteria and maintenance therapy between the two countries.