Extraosseous Ewing sarcoma arising in a chronically lymphedematous limb.

Ewing sarcoma is a highly aggressive small round cell malignant neoplasm of bone and soft tissue that typically is manifested in children and young adults. It is most commonly a primary bone tumor; however, extraosseous cases have been increasingly reported. We report a case of metastatic extraosseous Ewing sarcoma with the primary lesion occurring within a limb affected by primary lymphedema. Lymphedema, in this case, played a role not only in the genesis of the tumor because of the relative local immunosuppression but also in masking the development of the lower limb mass.