Isolated unilocular renal hydatid cyst: a rare diagnostic difficulty with simple cyst

Hydatid disease is endemic in many parts of the world. The location is mostly hepatic (75%) and pulmonary (15%), and only 10% of the cysts occur in the rest of the body. It may develop in almost any part of the body. Although hydatidosis can be present in all parts of the human body, urinary tract involvement develops in only 2-4% of all cases, and isolated renal cysts are extremely rare. There are no specific clinical symptoms or signs that will reliably confirm the diagnosis of renal echinococcosis. In addition, there is no laboratory finding that is pathognomonic for hydatid disease except for hydatiduria. Routine blood tests are generally normal except for eosinophilia which is found in only 50% of the cases. Radiological studies have a more important place in the preoperative diagnosis of renal hydatic disease. However, there is no specific sign on plain radiography or intravenous urography, and ultrasound or computed tomography cannot always show a hydatidosis as a specific lesion. From these reasons, sometimes it is difficult to differentiate between a unilocular hydatid cyst without mural calcification and a simple renal cyst. So, despite its rarity, hydatid disease should be included in the differential diagnosis of cystic lesions in solid organs or other anatomic sites, especially in endemic countries. We present herein a patient with isolated renal hydatid cyst mimicking a simple cyst treated successfully with complete excision.