CD99 and non-Hodgkin lymphoma: Additionally, negative staining for NKX2.2, CD99, desmin, S100, SOX10, HMB45, GATA3, CD45 (LCA), CD3, and CD20 further excluded diagnoses of Ewing sarcoma, rhabdomyosarcoma, melanoma, and the majority of non-Hodgkin lymphomas.