Periosteal Ewing sarcoma.

Purpose: To evaluate the imaging and histopathologic findings and clinical course of patients with periosteal Ewing sarcoma (PES).

Materials And Methods: Conventional radiographs, computed tomographic (CT) scans, and magnetic resonance (MR) images in 10 adolescents and one adult were evaluated for the extent and character of PES.

Results: Ten of 11 masses were in the proximal extremities and one in the fibula; nine were diaphyseal and two, metadiaphyseal. Radiographs and CT scans showed a subperiosteal mass that did not invade the medullary cavity, was contiguous with and elevated the periosteum, and produced a Codman triangle and periosteal reaction. No PES exhibited osseous or cartilaginous matrix calcifications. MR imaging and histopathologic examination helped confirm the sparing of cancellous bone and the subperiosteal location.

Conclusion: PES differs from the more common medullary and soft-tissue Ewing sarcomas in location, marked male predominance, and lack of presenting metastases. Except for the absence of matrix calcifications, PES resembles other periosteal sarcomas in imaging characteristics and a less aggressive clinical course.