Ewing Sarcoma Family of Tumors (ESFTs) of Renal Origin Presenting With Bone Metastases: A Case Report

We report a unique case of a female patient in her fifth decade of life who presented with groin pain and was found to have a right kidney mass measuring approximately 8 cm, in addition to multiple bone metastases. Both the nephrectomy specimen and the bone biopsy were found to belong to the Ewing sarcoma family of tumors (ESFTs). This was confirmed by immunohistochemical studies and fluorescence in situ hybridization (FISH) showing <i>EWSR1</i> gene rearrangement. Molecular analysis with next-generation sequencing (NGS) showed a type II <i>EWSR1:FLI1</i> gene fusion. The patient's disease progressed rapidly, and she passed away approximately three months after admission. Although extremely rare in the kidney, ESFT should be considered in patients who present with clinically aggressive kidney tumors.