Stone granuloma: a cause of ureteral stricture

Ureteral stricture is a recognized complication of ureteroscopy and ureteral stone fragmentation. Although most strictures are either asymptomatic or easily dilated, there are some strictures that result in progressive ureteral obstruction, do not respond to ureteral dilation and require operative intervention. A review of 125 percutaneous nephrostolithotomies for staghorn stone disease and 652 ureteroscopic stone fragmentations revealed 5 cases in which refractory ureteral strictures developed, requiring operative intervention. In 4 patients a "stone granuloma," embedded particles of calcium oxalate associated with macrophages and foreign body giant cells, was found with surrounding fibrosis and ureteral obstruction. In the remaining patient a suture granuloma from a recent ureterolithotomy was the source of the stricture. In each instance of stone granuloma the particles of calcium oxalate had become embedded in the wall as a consequence of ureteroscopic stone fragmentation and partial ureteral wall disruption. During ureteroscopy and intracorporeal lithotripsy every effort should be made to prevent calcium oxalate particles from becoming embedded in the ureteral wall. They are not inert and may cause irreversible stricture formation. To our knowledge, stone granuloma is a previously undescribed phenomenon and should be suspected when ureteral strictures that occur following ureteroscopy do not respond to endourological methods of management.