IgG 4-Positive Sclerosing Cholangitis Following Autoimmune Pancreatitis With Deranged CA19.9

Sclerosing cholangitis is an autoimmune condition characterized by lymphocytic infiltration within the biliary epithelium leading to multifocal stricturing of the biliary tree. Primary sclerosing cholangitis (PSC) is the most common type encountered clinically. However, a similar process may occur in conjunction with autoimmune pancreatitis (AIP), known as AIP-associated sclerosing cholangitis (AIP-SC). This subtype is associated with an elevated IgG4 level and the presence of a number of autoantibodies. AIP-SC shows good response to steroid treatment, distinguishing it clinically from PSC. The authors report a case of AIP-SC in a patient who had previously undergone a biliary bypass for AIP-induced chronic pancreatitis. The presentation of jaundice and grossly elevated tumor marker, CA19.9, raised the concern of malignancy. The uncertainty of the diagnosis was resolved when AIP-SC was confirmed on liver biopsy, with a concomitantly elevated serum IgG4 level. The disease went into remission with steroid treatment.