Extraskeletal Ewing's sarcoma presenting as a posterior mediastinal mass.

The Ewing's sarcoma family of tumors is an uncommon group of malignant neoplasms that may be located in both skeletal and extraskeletal regions. Extraskeletal Ewing's sarcoma (EES) is quite rare and predominantly involves the soft tissues of the trunk or the extremities. Herein, we report the case of a 19-year-old female patient who complained of left arm pain. Simple chest radiography revealed an opacity occupying almost the entire left hemithorax. Diagnostic imaging techniques demonstrated a solid contrast-enhanced mass in the posterior mediastinum. There was an evident mediastinal shift, and the left lung was collapsed. Even though lymphoma was considered as an initial diagnosis, a biopsy was taken and its histopathological analysis revealed EES. In the literature, there have been only a few case reports of ESS located in the mediastinum. We conclude that, although this is an unusual location, EES should be contemplated in the differential diagnosis of mediastinal masses.