CASE REPORT: Bile Duct Involvement in a Case of Autoimmune Pancreatitis Successfully Treated with an Oral Steroid

: In the case reported here, the characteristic features of AIP were evaluated by ultrasonography, computed tomography and endoscopic retrograde cholangiopancreatography, initially in the intrahepatic- and extrahepatic bile ducts, and later in the pancreas. In addition, histological examination revealed lymphocytic sclerosis around the intralobular bile ducts, as is reported in AIP, without chronic nonsuppurative destructive cholangitis or onion-skin-like appearance. Immunohistochemistry identified the infiltrating lymphocytes as T cells. Although hypergammaglobulinemia was observed with elevation of hepatobiliary and pancreatic enzymes, no other serological or physiological abnormalities suggestive of other systemic autoimmune diseases were detected. These findings progressed over a three-month period and were dramatically resolved within one month by steroid therapy. These observations support a novel clinical entity characterized by the presence of bile duct lesions similar to the pancreatic involvement seen in AIP that is distinct pathophysiologically, histologically, and therapeutically from the so-called autoimmune cholangitis or primary sclerosing cholangitis.