CT and Positron Emission Tomography/CT Findings of Mediastinal Extraskeletal Ewing's Sarcoma with Extensive Distant Metastasis: A Case Report.

Extraskeletal Ewing’s sarcoma (EES) is a rare malignant small round cell tumor of neural crest origin, which is histologically similar to the more common osseous Ewing sarcoma. Different from the osseous counterpart, it shows a wider age presentation, preferentially occurring in children and young adults, younger than 30 years (1, 2). The most frequent sites of occurrence are the chest wall, lower extremities and paravertebral region, but it rarely occurs in the mediastinum. The recently reported CT finding of mediastinal EES is a large, non-calcified mass with heterogeneous enhancement, frequently infiltrating to the adjacent tissues. In spite of its aggressive behavior, distant metastasis is rare (1, 3). Although positron emission tomography (PET)/CT findings of EES have been rarely reported, it has been reported to show relatively weak fluorodeoxyglucose (FDG) uptake, considering the growth pattern (4). We report a case of a 68-year-old man diagnosed as mediastinal EES with extensive hematogenous and lymph node metastasis by a CT and PET/CT.