Foreign body in the kidney associated with stone formation: report of a case

A 56-year-old woman was admitted to our hospital with the chief complaint of fever and right flank pain. She had had pyelolithotomy on the right kidney at another hospital eleven years earlier. Plain X-ray showed eight calcified shadows in the renal area. Excretory urograms showed slight hydronephrosis on both sides. Right pyelolithotomy was performed and it disclosed foreign body stones with nuclei of silk sutures used in the previous surgery. Including our case, nine cases of suture-thread stones in the upper urinary tract were found in the Japanese literature.