A case of eosinophilic cholangitis without bile duct stenosis diagnosed by bile duct biopsy.

Eosinophilic cholangitis (EC) is a rare benign disease that is often misdiagnosed as a malignancy due to the development of biliary stricture. This disease is generally diagnosed by liver biopsy or surgery. Herein, we report a case of EC diagnosed in an 86-year-old Japanese woman, who presented with fever, elevated eosinophil count, and elevated liver enzyme level, based on intraductal ultrasound evaluation showing bile duct wall thickening and bile duct biopsy of the same site. We diagnosed this case as EC based on the triad of wall thickening of the biliary system, histopathological findings of eosinophilic infiltration of the biliary tract, and reversibility of biliary abnormalities without treatment. Bile duct biopsy during endoscopic retrograde cholangiopancreatography (ERCP) is rarely used to confirm the diagnosis of EC without bile duct stenosis. For EC and cholecystitis associated with eosinophilia, bile duct biopsy under ERCP, which is less invasive, should be considered. This patient was older than the previously reported patients, and the value of a minimally invasive diagnosis was high.