Immunoglobulin G4-related lymphoplasmacytic sclerosing cholangitis that mimics infiltrating hilar cholangiocarcinoma: part of a spectrum of autoimmune pancreatitis?

Background: Autoimmune pancreatitis has been designated as sclerosing pancreatocholangitis, because this disease shows a high prevalence of bile-duct lesions. We present herein the clinical characteristics of unusual cases that show dominant bile-duct lesions and mimicking infiltrating hilar cholangiocarcinomas. Methods: Clinical and pathologic findings of 3 patients with immunoglobulin (Ig) G4 related sclerosing cholangitis who had no apparent pancreatic lesions comparable with autoimmune pancreatitis were analyzed. Observations: All patients were middle-aged or elderly individuals with slightly elevated serum IgG4 concentrations and showed long-segment narrowing of the bile-duct system, mimicking infiltrating hilar cholangiocarcinoma without significant pancreatic change. The first patient was treated with a corticosteroid, resulting in amelioration of the narrowing of the bile duct. The second patient underwent surgery based on a diagnosis of cholangiocarcinoma. In the third patient, the bile-duct stricture reversed spontaneously 1 month after the drainage procedure. Pathologic findings of the bile ducts for all patients disclosed significant lymphoplasmacytic infiltration, including abundant IgG4-bearing plasma cells. Conclusions: The use of IgG4 immunostaining in biopsy specimens of the bile duct may identify the presence of corticosteroid-responsive lymphoplasmacytic sclerosing cholangitis.