Ewing sarcoma/primitive neuroectodermal tumor of the kidney: A report of three cases

INTRODUCTION: Ewing sarcoma/Primitive neuroectodermal tumor of the kidney (ES/PNET) is a member of Ewing’s sarcoma family, occurring in young adults and has aggressive clinical behavior and poor prognosis. However, its discrimination from the renal cell carcinoma (RCC) is very difficult preoperatively. We present three cases of this rare disease that were managed in two academic centers. PRESENTATION OF CASES: Herein we report three cases of ES/PNET of the kidney, 2 young men complaining of right flank pain and gross hematuria and one young woman complaining of left subcostal pain. In two cases computerized tomography (CT) scan revealed huge renal masses which were excised by radical nephrectomy. Microscopic examination of the nephrectomy specimen showed primitive neuroectodermal tumor features which confirmed by immunohistochemistry (IHC). Two of 3 patients were treated with adjuvant chemotherapy and the third patient with neoadjuvant chemotherapy. They were symptom-free until now. DISCUSSION: The clinical course and prognosis of ES/PNET are different from renal cell carcinoma (RCC) and definite pathologic diagnosis is necessary for optimum treatment. For definite diagnosis, in addition to cytogenetic analysis; other techniques may be needed; such as fluorescent in situ hybridization (FISH), reverse transcriptase-polymerase chain reaction (RT-PCR) of the t (11; 22) translocation or the EWS-FLI and related gene fusions [1]. CONCLUSION: Up to our knowledge and search in English literature, this is the first case series that was reported from a major referral center from our country, Iran.