# Extra-skeletal Ewing sarcoma in a 63-year-old female with a history of triple-negative breast cancer: a case report and literature review

## TL;DR

A 63-year-old woman with a history of breast cancer was diagnosed with rare extra-skeletal Ewing sarcoma after initial misdiagnosis.

## Contribution

This case highlights the diagnostic challenges and management of EES in older adults with a cancer history.

## Key findings

- EES was confirmed via RNA sequencing showing the EWSR1-FLI1 fusion gene.
- The patient received neoadjuvant chemotherapy and tumor resection.
- EES can occur in older patients, leading to potential misdiagnosis.

## Abstract

Ewing sarcoma (ES), particularly Extra-skeletal Ewing sarcoma (EES), is a rare, aggressive tumor predominantly affecting adolescents and young adults, yet it can occur in older patients, leading to misdiagnosis and delay in treatment. The standard approach includes surgical resection, chemotherapy, and radiation therapy for unresectable disease. This case report presents a 63-year-old female patient with a history of triple-negative breast cancer, who was discovered to have a soft tissue tumor in the left medial thigh. Initially misdiagnosed as rhabdomyosarcoma, the diagnosis of EES was ultimately confirmed via RNA sequencing revealing the EWSR1-FLI1 fusion gene. She underwent neoadjuvant chemotherapy followed by radical resection of the tumor.