Mild inflammatory cell infiltration was defined by a small number of inflammatory cells that were scattered throughout the HPF. In severe inflammation, many diffuse inflammatory cells were observed. Samples were considered to have moderate inflammation when they showed between mild and severe inflammation. Although AZD1208 obliterative phlebitis is a characteristic histological feature of IgG4-SC, it was not assessed in the present study because it usually occurs in relatively large veins that were not sampled by the endoscopic biopsies. IgG4 immunostaining was carried out with an autostainer (HX System

Benchmark, Ventana Medical Systems, Tucson, AZ, USA) following the manufacturer’s instructions. The primary antibody was an anti-IgG4 mouse monoclonal antibody (ZYMED Laboratory, San Francisco, CA, USA). Before incubating with the primary antibodies, the sections were pretreated with proteinase. IgG4-positive plasma cells were counted in the most inflamed HPF (10× eyepiece and 40× lens) in both the Vater’s ampulla and bile duct biopsies. The degrees of inflammatory cell infiltration (mild/moderate/severe),

plasma cells, eosinophils, and the numbers of IgG4-positive plasma cells on ampullary and bile duct biopsies were compared AUY-922 between the three groups using Tukey’s test. The numbers of IgG4-positive plasma cells in the ampullary and bile duct biopsies, and the clinical characteristics (swelling of Vater’s ampulla or the pancreatic head) of patients with IgG4-SC were also analyzed using χ2-test and Fisher’s test. A value of P < 0.05 was considered statistically significant. All of the analyses were carried out using spss II for Windows, Version 8.0.1. J (SPSS, Chicago, IL, USA). The results of the histological examination of the ampullary biopsies are summarized in Table 1. There were no significant differences

in the degrees of inflammatory cell infiltration, plasma cell infiltration (> 20 cells/HPF) and eosinophil infiltration (> 20 cells/HPF) among three disease groups. Three IgG4-SC cases had severe inflammatory cell infiltration (Fig. 1c), although they were not associated with the irregular fibrosis that is typically observed in surgical AIP or IgG4-SC specimens. The bile 上海皓元 duct biopsies showed inflammatory cell infiltration, fibrosis and stromal edema to varying degrees in each case of IgG4-SC. Of the 29 IgG4-SC patients, 10 (34%) had plasma cell infiltrations greater than 20 cells/HPF, although this increase was not significantly greater than that observed in samples from PSC and pancreatobiliary carcinoma patients (Table 1). Interestingly, five of these cases (17% of all IgG4-SC patients, four with AIP and one with cholangitis only) showed lymphoplasmacytic infiltration intermixed with irregular fibrosis, which was corresponding to lymphoplasmacytic sclerosing pancreatitis and cholangitis (a pathological term of AIP/IgG4-SC) (Figs 1f,2a).