A case of retroperitoneal abscess: an unusual complication of cholecystitis and choledocholithiasis.

A man, 73 years old, who developed acute biliary tract infection complicated with retroperitoneal abscess formation in iliopsoas region was reported. The magnetic resonance imaging was especially effective to delineate the lesion, extending from the subhepatic down to the iliopsoas muscle. The echo-guided fine needle aspiration technique was successful to make the lesion subside.