Eosinophilic cholangitis mimicking IgG4-related sclerosing cholangitis in an older female patient.

Eosinophilic cholangitis (EC) is a rare, benign disorder characterized by eosinophilic infiltration of the bile ducts, often mimicking cholangiocarcinoma or sclerosing cholangitis. In this report, we present the case of an 84-year-old woman who presented with biliary stricture, peripheral eosinophilia, and elevated serum IgG4 levels. Liver biopsy revealed prominent eosinophilic infiltration without definitive findings of IgG4 sclerosing cholangitis (IgG4-SC). The patient responded promptly to corticosteroid therapy, although biliary abnormalities on magnetic resonance cholangiopancreatography persisted for another 16 months. This case highlights the diagnostic challenge of differentiating EC from IgG4-SC and underscores the importance of considering EC in patients with biliary strictures and eosinophilia.