Case Report A Case of Hydatid Cyst Mimicking Kidney Tumor Ahmet Camtosun , Hüseyin Çelik , Ahmet Yıldız , Ramazan Altıntaş , Cemal Taşdemir Department of Urology, İnönü University School of Medicine, Malatya, Turkey ORCID IDs of the authors: A.C. 0000-0002-5390-9088; H.Ç. 0000-0002-7180-4845; A.Y. 0000-0003-2968-6758; R.A. 0000-0003-3145- 3005; C.T. 0000-0001-5710-6891. A 45-year-old male patient presented with left flank pain that started a month ago. There was no history of fever or pyuria. Vital signs were normal. The rest of the systemic examination was unremarkable. There were no pathological findings on urinalysis or urine cytology. Ultrasonography revealed an 8×6.2×6 cm heterogeneous exophytic trending lesion at the lower pole of the left kidney. The lesion's walls were seen to be calcified in places, and the margin between the kidney and lesion was indistinct. It could not be differentiated by ultrasonography if the lesion is a complicated cyst or a mass. Magnetic resonance imaging scan of the upper abdomen also revealed a 9×7.5×7 cm cortical–parapelvic localized lesion at the lower pole of the left kidney, extending exophytically to the inferior. Given the possibility that the lesion is malignant, nephrectomy was planned. A laparoscopic approach was performed. Histopathological diagnosis was hydatid cyst. Enzyme-linked immunosorbent assay test for hydatid disease was negative. Albendazole 10 mg/kg twice a day was administered postoperatively for 3 weeks. Keywords: Kidney, cancer, hydatid cyst INTRODUCTION Hydatid cyst disease, also known as echinococcosis, is a parasitic infestation caused by Echinococcus granulosus, a ces- tode from the Taeniidae family (1). Carnivores, such as wolves, foxes, and especially dogs, are definitive hosts for the par- asite, and herbivores, such as sheep, cows, and goats, are intermediate hosts. Humans are incidental hosts. They do not play a role in the transmission cycle and may be infested through contact with a definitive host or oral ingestion of water or vegetables contaminated by the eggs of the parasite. Hydatid disease may affect many parts of the human body. Ap- proximately 40%–80% of patients with primary hydatid disease have single-organ involvement, and it commonly affects the liver (61%) and lungs (18.7%) in single-organ involved cases. However, primary kidney hydatid cysts are extremely rare (2.6%) (2). Cysts in the kidney can cause hematuria or flank pain (3). In some patients, as a result of the rupture of the cyst in the collecting system, hydatiduria may occur. The diagnosis is based on imaging and serological tests. In radiological and serological studies, renal hydatid disease cannot be diagnosed preoperatively in 1 out of 3 patients (4). Here, we present a case of a 45-year-old man with primary renal hydatid disease. CASE PRESENTATION A 45-year-old male patient presented with left flank pain that started a month ago. There was no history of fever or pyuria. His vital signs were normal. Costovertebral angle tenderness was revealed on physical examination. The rest of the systemic examination was unremarkable. He had a history of Behcet’s disease, but there was no oral or genital ulcer on admission. Laboratory studies presented normal eosinophil rate (2.7%), normal renal functions (blood urea 12.71 mg/ dL and creatinine 0.74 mg/dl), and normal liver function tests. There were no pathological findings on urinalysis or urine cytology. Ultrasonography revealed an 8×6.2×6 cm heterogeneous exophytic trending lesion at the lower pole of the left kidney. The lesion’s walls were seen to be calcified in places, and the margin between the kidney and lesion was indistinct. It could not be differentiated by ultrasonography if the lesion is a complicated cyst or a mass. Magnetic resonance imag- ing (MRI) scan of the upper abdomen also revealed a 9×7.5×7 cm cortical–parapelvic localized lesion at the lower pole of Corresponding Author: Ahmet Camtosun E-mail: drcamtosun@yahoo.com ©Copyright 2019 by Cyprus Turkish Medical Association - Available online at cyprusjmedsci.com Received: 22.06.2018 Accepted: 20.12.2018 DOI: 10.5152/cjms.2019.100 70 Cite this article as: Camtosun A, Çelik H, Yıldıız A, Altıntaş A, Taşdemir C. A Case of Hydatid Cyst Mimicking Kidney Tumor. Cyprus J Med Sci 2019; 4(1): 70-2. This study was presented at the 4 th National Minimal Invasive Urological Surgery Congress, 3-6 March 2016, Antalya, Turkey