Isolated Renal Hydatid Cyst Mimicking Renal Cell Carcinoma: A Diagnostic Dilemma

Context : Hydatidosis due to Echinococcus granulosus is a parasitic zoonosis with worldwide occurence. The most common locations are liver and lung. Occasionally, it may mimic intra abdominal tumour. Aims: Hydatid disease of the urinary tract is uncommon, occurring in only 2 to 3% of all cases. This case is presented with the aim of highlighting a giant renal echinococcus cyst, misdiagnosed as renal malignancy on imaging. Setting: The misdiagnosis of renal carcinoma was made in the case of a 65-year-old man. Materials and Methods: The patient presented with colicky pain in right flank with fever, nausea and vomiting. Right kidney was palpable with leucocytosis and proteinuria. X ray abdomen revealed ring calcifications in right upper quadrant. Ultrasonography (USG) and computerised tomography (CTshowed a soft tissue mass in right kidney. Intravenous urography with conventional tomography 15 minutes after contrast demonstrated nil nephrogram in right kidney. CT findings were suggestive of renal cell carcinoma. Conclusions: Hydatid cyst can attain large dimensions and can easily be misdiagnosed as a tumour. Despite its rarity, hydatid disease should be considered in the differential diagnosis of renal space-occupying lesions.