Pathology of autoimmune pancreatitis: a review of Japanese and Western reports

Abstract

Growing evidence indicates that, pathologically, there are different groups in "autoimmune pancreatitis (AIP)". The majority of Japanese cases belong to lymphoplasmacytic sclerosing pancreatitis, which is characterized by dense fibrosis with lymphoplasmacytic infiltrates, periductal inflammation, obliterative phlebitis and numerous IgG4-positive plasma cells. In the west, however, there is another type called idiopathic duct-centric chronic pancreatitis or AIP with granulocytic epithelial lesions, in which, in addition to lymphoplasmacytic infiltrates in the exocrine system, the duct epithelium and lumen are infiltrated by neutrophils. The different prevalence of the latter is probably the best reason why the clinicopathological features of AIP are different between Japan and the West.