Extraosseous Ewing's sarcoma/peripheral primitive neuroectodermal tumour of the kidney: a case report and literature review.

BACKGROUND: Extraosseous Ewing's sarcoma/peripheral primitive neuroectodermal tumours(EWS/pPNETs) of the kidney are rare. Signs and symptoms are atypical in EWS patients. Presenting symptoms include haematuria, abdominal pain, or a palpable mass. A comprehensive review of the literature shows that it is difficult to make an accurate diagnosis based on physical examination alone. The imaging findings of EWS/pPNETs are nonspecific. We used contrast-enhanced ultrasound (CEUS) to diagnose an EWS/pPNET in our patient, which had never been reported previously to our knowledge.

CASE PRESENTATION: This article reports the case of a 20-year-old female with an abdominal mass and gross haematuria for 1 month. The ultrasound revealed a hypoechoic mass with a clear margin at the lower pole in the left kidney. CEUS demonstrated signs of annular enhancement and heterogeneous enhancement of the tumour, and simultaneous wash-in was predominant. Computed tomography images showed an elliptical low-density tumour. The patient underwent a left kidney resection, and the pathological diagnosis was an EWS/pPNET. Twenty-one days after the kidney operation, the patient underwent 8 cycles of a CAV (vinorelbine, ifosfamide, epirubicin) + IE (isocyclophosphamide, etoposide) chemotherapy regimen. Subsequently, radiotherapy (dose: 45 Gy, radiation field:the tumour bed following surgical resection) was administered for nearly 30 days. The patient had no signs of local recurrence or metastasis within a follow-up of 4 years.

CONCLUSIONS: As a radiation-free, inexpensive, convenient, and repeatable examination method, ultrasound was the primary choice for kidney examination. Early CEUS was helpful to make an accurate diagnosis. Surgery and adjuvant radiation or chemotherapy administered in a timely manner can prevent further deterioration.