CD99 and Ewing sarcoma: The initial diagnostic work-up was muddied by radiographic suggestion of uterine origin, histologic identification of uterine involvement and diffuse positivity for Cyclin D1, KIT and CD99, which raised the diagnostic possibility of high-grade endometrial stromal sarcoma. However, molecular testing that revealed EWSR1::FLI fusion, indicative of Ewing sarcoma.