Computed Tomography Imaging of Anterior and Middle Mediastinal Ewing Sarcoma/Primitive Neuroectodermal Tumors

We describe the computed tomography (CT) imaging features of Ewing sarcoma (EWS)/primitive neuroectodermal tumors (PNETs) arising in the anterior and middle mediastinum.The CT imaging findings of 6 cases of anterior and middle mediastinal EWS/PNETs were reviewed retrospectively. All 6 patients were examined with chest radiographs and CT, and 4 patients underwent isotope bone scans.The average patient age was 40 years. Results using unenhanced CT showed lobulated, heterogeneous masses with patchy, necrotic foci in 5 cases, and one small, oval homogenous mass in the sixth case. There was no calcification in any of the cases. The contrast-enhanced CT results demonstrated that there were 4 cases of heterogeneous enhancement and one case of homogeneous enhancement. All the masses were ill-defined, and in 4 cases, the masses were displaced and encompassed the adjacent great vessels. The tumors directly infiltrated the anterior chest wall in 3 cases, and in one of these cases had eroded the sternum. Four cases demonstrated pleural effusions. Isotope bone scans showed distant bone metastases at diagnosis in 2 cases.EWS/PNETs in the anterior and middle mediastinum appear as ill-defined, heterogenerous masses that are not distinguishable from other, more common, causes of mediastinal masses, based on their CT features.