Abstract
Ewing's sarcomas and peripheral primitive neuroectodermal tumors (ES/PNETs) are high grade malignant neoplasms. These malignancies are characterized by a chromosome 22 rearrangement, arise from bone or soft tissue, predominantly affect children and young adults, and are grouped in the Ewing family of tumors. Multimodality treatment programs are the treatment of choice. Primary localization of ES/PNET in the mediastinum is extremely rare. We describe a case of ES/PNET presenting as a mediastinal mass with tracheal compression and initial signs of superior vena cava in a 66-year-old woman.