Unilateral ureteral obstruction secondary to rupture of liver echinococcal cyst

We report a case of ureteral obstruction by reactive retroperitoneal fibrosis secondary to rupture of a liver echinococcal cyst after minimal blunt flank trauma. The patient presented initially with a cyst-cutaneous fistula and was treated with mebendazole, since surgery was refused. Unilateral ureteral obstruction due to reactive dense retroperitoneal fibrosis developed 2 years later, which presumably was initiated by intense inflammatory reaction to the cyst content. Diagnosis was established by excretory urography, ultrasonography and computerized tomography, and was histologically confirmed. Hydronephrosis and hydroureter resolved following ureterolysis. This complication is anticipated to be encountered more frequently with the use of the new potent anthelmintic agents, which may successfully prevent daughter cyst formation but fail to abolish reactive retroperitonitis.