Radiological changes under effect of mebendazole on univesicular hydatid cysts in the liver and lung

Mebendazole was given to a patient who had developed four univesicular hydatid cysts in 16 months following initial infection (two in the liver and two in the lungs). The size of the cysts varied from five to ten centimeters in diameter. The therapeutic effect of the drug was assessed by ultrasound, computed tomography and chest x-ray examination. A completely split wall was only observed in the smallest hepatic cyst after a three-month period with a dose of 2.4 g per day (50 mg/kg/day). Peak serum level of mebendazole was 45.2 ng/ml. Thereafter, the intake was increased to 4.5 g per day (86.5 mg/kg/day) during one year. Peak drug serum level was 67.7 ng/ml. Dramatic radiological changes were subsequently noted in the other cysts. These radiological changes precisely mimicked those changes observed during the natural course of healthy cysts when they become complicated by ageing. We have found that ultrasound and chest x-ray proved to be the best method for assessing the therapeutic efficacy of medical treatment for univesicular cysts in the liver and lung. The asynchronous evolution observed in these lesions under such different drug schedules seems to depend on the size and location of the cyst, and on serum mebendazole levels as well as length of treatment.