Primary Renal Ewing Sarcoma With Extensive Metastatic Disease at Diagnosis: A Case Report and Literature Review

This is the authors' abstract. We don't add key points for this paper.

Primary renal Ewing sarcoma (PRES) is an exceedingly rare and aggressive neoplasm. We report a 43-year-old woman with left flank pain and a palpable abdominal mass. Imaging revealed a large renal mass with adrenal, pulmonary, and osseous involvement, staged cT4N1M1. Biopsy showed a small round blue cell neoplasm positive for CD99, NKX2.2, and FLI-1, with EWSR1-FLI1 fusion confirmed by FISH. Palliative systemic chemotherapy achieved partial symptom control, and the patient remains under multidisciplinary follow-up. This case underscores the need for integrated morphological, immunohistochemical, and molecular diagnosis and shows that multimodal treatment can achieve clinical response despite metastatic disease.