[1682] Pathological Differences between IgG4-Related Sclerosing Cholangitis with and without Autoimmune Pancreatitis

Kenichi Harada, Yasuni Nakanuma. Kanazawa University Graduate School of Medicine, Kanazawa, Ishikawa, Japan

Background: IgG4-related sclerosing cholangitis (IgG4-SC) usually accompanies autoimmune pancreatitis (AIP), and IgG4-SC without AIP clinicopathologically mimics primary sclerosing cholangitis (PSC) and cholangiocarcinoma. In this study, we examined pathological differences between IgG4-SC with and without AIP.
Design: Partial hepatectomy and bile duct resection specimens were obtained from 7 patients with IgG4-SC accompanied by AIP (male/female = 6/1, average age 66 yrs) and 5 IgG4-SC without AIP (all male, average age 71 yrs). Using paraffin sections, in addition to HE and EVG staining, immunohistochemistry for IgG4 was performed.
Results: Location of the affected bile ducts: In IgG4-SC with AIP, affected bile ducts were in the middle and lower parts of common bile ducts, but intrahepatic bile ducts and hilar bile ducts were not involved in any cases. In constrast, all cases of IgG4-SC without AIP accompanied hilar hepatic lesions and were also found to various degrees in the upper part of common bile ducts and branches of hepatic ducts. Moreover, inflammatory pseudotumors were found in the hepatic hilus in 2 cases of IgG4-SC without AIP. Histology: Pathological findings of common bile ducts were common features of IgG4-related diseases such as marked lympho-plasmacytic infiltration, follicle formation, fibrosis, obliterative phlebitis, and numerous IgG4-positive cells in the intraductal wall and periductal area, irrespective of being with or without AIP. Biliary epithelium was well-preserved and inflammation was noted in peribiliary glands and the peri-nerve bundle compared with superficial mucosa. In IgG4-SC without AIP, dilatation and stricture of hilar bile ducts, similar to PSC, and proliferation and dilatation of the peribiliary gland were found in some cases. In the hepatic hilus, IgG4-positive cells broadly infiltrated and were noted in fibrous areas and the perineural bund, compared with the periductal area. Biliary intraepithelial neoplasia (BilIN): BilIN lesions were found in 2 of 7 cases of IgG4-S C with A IP and 3 of 5 cases of IgG4-SC without AIP. Erosion: Significant findings of neutrophil infiltration were not seen in IgG4-SC with AIP, but erosive change with neutrophils was found in hilar bile ducts of 3 of 5 cases with IgG4-SC without AIP.
Conclusions: Histology of common bile ducts in IgG4-SC without AIP was basically the same as that in IgG4-SC with AIP; however, IgG4-SC without AIP involved hepatic hilar lesions such as by dilatation and stricture of hilar bile ducts, BilIN, and erosion, suggesting that these findings complicate the differentiation of IgG4-SC without AIP from PSC and cholangiocarcinoma.
Category: Liver

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 157, Tuesday Afternoon


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