AIM: To evaluate the histopathological and radiological findings of the gallbladder in patients with autoimmune pancreatitis (AIP).METHODS: The radiological findings of the gallbladder of 19 AIP patients were retrospectively reviewed.Resected gallbladders of 8 AIP patients were examined histologically and were immunostained with antiIgG4 antibody. Controls consisted of gallbladders resected for symptomatic gallstones (n=10) and those removed during pancreatoduodenectomy for pancreatic carcinoma (n=10), as well as extrahepatic bile ducts and pancreases removed by pancreatoduodenectomy for pancreatic carcinoma (n=10).RESULTS: Thickening of the gallbladder wall was detected by ultrasound and/or computed tomography in 10 patients with AIP (3 severe and 7 moderate);in these patients severe stenosis of the extrahepatic bile duct was also noted. Histologically, thickening of the gallbladder was detected in 6 of 8 (75%) patients with AIP; 4 cases had transmural lymphoplasmacytic infiltration with fibrosis, and 2 cases had mucosal-based lymphoplasmacytic infiltration. Considerable transmural thickening of the extrahepatic bile duct wall with dense fibrosis and diffuse lyphoplasmacytic infiltration was detected in 7 patients. Immunohistochemically, severe or moderate infiltration of IgG4-positive plasma cells was detected in the gallbladder, bile duct, and pancreas of all 8 patients, but was not detected in controls.CONCLUSION: Gallbladder wall thickening with fibrosis and abundant infiltration of IgG4-positive plasma cells is frequently detected in patients with AIR We propose the use of a new term, sclerosing cholecystitis, for these cases that are induced by the same mechanism as sclerosing pancreatitis or sclerosing cholangitis in AIP.