A Kidney Hydatid cyst with No Conclusive Diagnostic Radiologic Evidence: A Case Report

[Background]Hydatid disease is a zoonotic parasitic infection that affects humans in many parts of the world, including Iran. It is caused by the larval stage of a tapeworm called Echinococcus. Human is an intermediate host infected accidentally by the ingestion of eggs excreted in the feces of dogs. This infection most commonly involves the liver and lung. Other site localizations are rare including kidney that is seen in 2% to 4% of cases.[Case Presentation]Here we report a 9-year-old boy with kidney involvement in a village near Poldasht city, West Azerbaijan, Iran, admitted on Jan 2013. He referred to our hospital with a left upper quadrant (LUQ) mass without any other symptoms, which was discovered by his mother accidentally. Sonography and CT scan with and without contrast revealed large hypodense fluid containing a mass arising from the left kidney that stretched renal parenchyma. Surgery consult was done and radical nephrectomy with left adrenalectomy and retroperitoneal lymphadenectomy due to the suspicion of malignancy was performed. In addition to surgery, he received the first dose of chemotherapy for Wilms tumor and after the pathologic report, albendazole started for him. A definitive presurgery diagnosis is not always possible by radiographic evidence. Therefore, the hydatid disease should be in the differential diagnosis of renal mass. Only surgery and pathologic findings can confirm the diagnosis. In our case, due to the lack of a definitive radiologic evidence for hydatid diagnosis, we did not start albendazole presurgery and albendazole started and continued for six months after the pathologic report confirmed the hydatid disease.[Conclusions]We recommend that albendazole starts in endemic areas for abdominal masses with a non-definitive diagnosis.