Biliary metal stent as a nidus for bile duct stone.

Several cases of recurrent stone formation caused by a surgical material as a nidus have been reported. Recently, we experienced one case in which a migrated metal stent might have been served as a nidus for common duct stone formation. The diagnosis was confirmed by ERCP, the stone was successfully removed with endoscopic therapy. Six years ago, she had undergone a lithotripsy using a percutaneous cholangioscopy (PTCS) because of intrahepatic bile duct stones. Six years later, she developed abdominal pain in the right upper quadrant. ERCP revealed the dilated extrahepatic bile duct and left intrahepatic bile duct and the presence of a large elongated freely mobile filling defect suggestive of common bile duct stone containing metal mesh in the distal common bile duct. The removed stone with endoscopic sphincterotomy was soft and dark brown in color with metal stent.