Extraosseous Ewing's sarcoma. Computed tomography evaluation before and after chemotherapy.

Fourteen patients with extraosseous Ewing's sarcoma were evaluated by computed tomography (CT) and conventional radiography. The sites of involvement were in the lower extremities (six cases), the chest wall (four), pelvis (two), and the paravertebral region (two). In seven cases, the initial contrast-enhanced CT disclosed a necrotic soft tissue mass in four, two of them with peripheral enhancement. In three cases, the mass was homogeneous and did not enhance. CT enabled us to detect the size of the mass, the integrity of adjacent bone and medullary cavity, and to determine the presence or absence of metastases. CT was useful for evaluation of the patients' tumor response to treatment. In three of four patients treated with chemotherapy, CT showed evidence of a dramatic initial response. In one patient who was resistant to chemotherapy, surgical methods were required.