A 25-year-old presented with a lesion on the left elbow, which was thought to a be a subcutaneous cyst. The lesion had been present for at least one year prior to excision. Grossly, it appeared to be cystic with mixed areas of hemorrhage. Immunohistochemically, the tumor cells are positive for desmin and negative for CD34, CD31, AE1/AE3, S-100, SOX-10, and Alk. Also, FISH showed findings consistent with an EWSR1 gene rearrangement.
Kyle Perry, M.D.
Fellow, Bone and Soft Tissue Pathology
Andrew Folpe, M.D.
Consultant, Division of Anatomic Pathology
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine