Primary Subcutaneous Ewing Sarcoma Presented as Pseudo Aneurysmal Subcutaneous Tumor

Background Extraskeletal Ewing's sarcoma is a rare malignant tumor of mesenchymal origin, which is histologically similar to primary osseous Ewing's sarcoma. It has been well described in deep soft tissues. However, location in cutaneous or subcutaneous tissue has rarely been reported. Being seen principally in children, it can be seen, rarely, in old men. Case report We present a case of subcutaneous Ewing sarcoma within the left shoulder of a 49-year-old man, without osseous involvement. Physical examination suggested a vascular tumor. Histologically, it was a small round cell tumor that marked strongly for CD99. The diagnosis of subcutaneous Ewing sarcoma was performed. Conclusion Ewing sarcoma is a rare malignant small round cell tumor of the skin and subcutaneous tissue. It should be differentiated from other cutaneous neoplasms composed of small round cells.