IgG4-related sclerosing cholangitis and autoimmune pancreatitis: Histological assessment of biopsies from Vater's ampulla and the bile duct

Background and Aim: Autoimmune pancreatitis is commonly associated with immunoglobulin (Ig) G4-related sclerosing cholangitis (IgG4-SC). The discrimination between IgG4-SC and pancreatobiliary malignancies or primary sclerosing cholangitis (PSC) is now an important issue. The present study was carried out to examine the usefulness of endoscopic biopsies from Vater's ampulla and the bile duct to diagnose IgG4-SC. Methods: The present study included 29 IgG4-SC patients (26 with both pancreatitis and cholangitis, and 3 with cholangitis only), 6 PSC patients, and 27 pancreatobiliary carcinoma patients. All patients underwent endoscopic biopsies from Vater's ampulla and the common bile duct. Biopsied specimens were histologically examined using immunostaining for IgG4. Results: For the ampullary and bile duct biopsies, the IgG4-SC samples had a significantly greater number of IgG4-positive plasma cells than the PSC or pancreatobiliary carcinoma specimens. In addition, bile duct biopsies from five patients (17%) with IgG4-SC showed diffuse inflammatory cell infiltration with irregular fibrosis corresponding to the histological features of lymphoplasmacytic sclerosing pancreatocholangitis. Based on the threshold of 10 IgG4-positive plasma cells per high power field, the diagnostic rates of the ampullar and bile duct biopsies were both 52% (15/29 cases). Twenty-one patients (72%) had more than 10 IgG4-positive plasma cells in at least one biopsy. The bile duct biopsy was significantly valuable for IgG4-SC patients with swelling of the pancreatic head. Conclusion: The present study suggested that ampullar and bile duct biopsies are useful for diagnosing IgG4-SC.