Abstract
Erdheim-Chester disease (ECD) is an exceedingly rare and aggressive disease characterized by foamy CD68 + CDa-histiocytic infiltration into multiple tissues and organs. Only 1,500 cases have been diagnosed since 1930 when ECD was first described. Biliary tract involvement of ECD has only been reported in the literature once. We report a case of ECD causing extrahepatic biliary obstruction without significant bile duct dilation, mimicking primary sclerosing cholangitis or IgG4 disease.