Extraskeletal Ewing's sarcoma presenting as a mediastinal mass.

Ewing's sarcoma family of tumors is part of a rare group of malignant neoplasms with small blue, round-cell morphology on hematoxylin and eosin stain, expressing CD99, C-Kit, and Bcl2, and sharing the presence of the translocation t(11:22). Extraskeletal Ewing's sarcoma is a rare disease that typically involves the soft tissues of the trunk or extremities. We describe a case of extraskeletal Ewing's sarcoma presenting as a mediastinal mass in a 16-year-old boy.