CD99 and Ewing sarcoma: The translocation of the EWSR1 gene on to chromosome 22p12 next to the FLI1 gene may cause upregulation of insulin-like growth factor 1, playing a key role in cellular proliferation.[3] The common translocation and a strong membranous expression of CD99 could unify the diagnosis of extraosseous Ewing sarcoma.[4] A 48-year literature review from 1970 to 2018 revealed that <30 cases of primary vaginal Ewing's sarcoma had been previously reported,[1,2,4] and few literatures had discussed the imaging findings of primary vaginal Ewing sarcoma.