Primary Renal Primitive Neuroectodermal Tumor/Ewing’s Sarcoma Imaging and Pathologic Findings of a Patient with a Nine Year, Eight Month Disease Free Period: Case Report and Review of Literature

INTRODUCTION Primitive neuroectodermal tumor (PNET)/Ewing's sarcoma (EWS) belongs to a family of neoplasms that are presumed to originate from the neuroectodermal crest. PNET/EWSs are highly aggressive malignancies that usually present in the form of bone or soft tissue masses and usually affect adolescents and young adults. Primary PNET/EWS of the kidney is very rare. CASE PRESENTATION We present the case of a 32-year-old female patient with primary renal PNET/EWS diagnosed nine years and eight months earlier. The patient presented with acute flank pain in the left lumbar region, hematuria, and episodes of high body temperature of 40°C. Abdominal ultrasound (US) and subsequently performed computed tomography (CT) revealed a large renal mass of heterogenous structure. The kidney tumor had central necrotic hypodense areas and strongly peripherally enhanced solid parts on postcontrast CT images. Immunohistochemistry revealed positivity for CD99 and neuron-specific enolase (NSE). Tumor cells were negative for CD3, CD 20, chromogranin, synaptophysin, vimentin, and neurofilament. Reverse transcription polymerase change reaction (RT-PCR) revealed EWS/FL1 translocation type 2. The patient underwent nephrectomy and polychemotherapy. The follow-up nine years and eight months after the diagnosis showed no evidence of tumor. CONCLUSIONS PNET/EWS should be included in the differential diagnosis of renal tumors in symptomatic young adults. Patients with localised PNET/EWS treated with a combination of surgery and chemotherapy have an excellent chance of long-term survival, as in the case we have presented.