01) (Table 3). In contrast, there was no significant difference in the number of IgG4-positive cells in the ampullary biopsies between patients with and without pancreatic head swelling. There were no complications related to ERCP or the biopsy, such as post-ERCP pancreatitis or cholangitis and bile duct perforation, in any of the patients. The results obtained from the present study can be summarized as follows: (i) out of 29 patients with IgG4-SC, 21 (72%) had more than 10 IgG4-positive plasma cells per HPF in at least either their ampullary or bile duct biopsy; (ii) compared between biopsies from Vater’s ampulla and the bile duct, the increased

number of IgG4-positive plasma cells was the only histological feature that could be examined to diagnose IgG4-SC in Dabrafenib ic50 ampullar biopsies. In contrast, eosinophil infiltration, as well as the

number of IgG4-positive plasma cells, is a useful feature in bile duct biopsies; (iii) www.selleckchem.com/products/VX-770.html in the bile duct biopsies, 10 patients had a large number of plasma cells (> 20/HPF). Five of these patients also had lymphoplasmacytic infiltration intermixed with irregular fibrosis, which are histological features that presumably correspond to lymphoplasmacytic sclerosing pancreatitis and cholangitis; and (iv) the bile duct biopsies were especially useful for IgG4-SC patients with pancreatic head swelling. Similar to previous reports, the present study also showed that AIP patients had a significantly higher number of IgG4-positive plasma cells in their ampullary

MCE biopsies than patients with PSC and pancreatobiliary carcinomas. Kubota et al. reported that 18 of 27 patients (67%) with AIP had more than 10 IgG4-positive plasma cells in their ampullary biopsies.14 Similarly, Kamisawa et al. reported that 8 of 10 patients (80%) were highly IgG4-positive (≥ 10 cells/HPF).15 Although the diagnostic rate of the current study was the lowest among the three endoscopic studies, 62% (41/66) of the total patients of the three studies had more than 10 IgG4-positive cells. AIP is typically diagnosed based on a combination of serological, radiological and pathological examinations.19 As much data have accumulated in this field, most AIP cases can be diagnosed based on serum IgG4 concentrations and characteristic radiological features.20–22 However, in some cases it is still difficult to differentiate AIP from pancreatic malignancies. For such cases, IgG4 immunostaining of ampullary biopsies might be one tool to facilitate the diagnosis of IgG4-SC or AIP. For pathologists, it is not difficult to count the number of IgG4-positive cells in biopsied specimens, although it might be harder to interpret the number of positive cells. A pathological diagnosis is usually based on hematoxylin–eosin-stained specimens. Therefore, pathologists might hesitate to make a definitive pathological diagnosis of IgG4-SC or AIP based only on the number of IgG4-positive plasma cells in ampullary biopsies.