PECAM1 and Ewing sarcoma: There are very few immunohistochemical studies of telangiectatic osteosarcomas; however, one study showed them to be immunoreactive for SATB2 and immunoregulative for CDK4, MDM2, panCK, CD31, desmin, NKX2.2, and TLE1, excluding angiosarcoma, intraosseous rhabdomyosarcoma, Ewing's sarcoma, and synovial sarcoma [10].