Immunohistochemistry was performed and tumor cells exhibited positive expression for CD99 (rabbit monoclonal, clone EP8, Biocare Medical), vimentin (mouse monoclonal, clone V9, Biocare Medical), and FLI-1 (mouse monoclonal, clone G146–222, BioSB) while being negative for glial fibrillary acidic protein (GFAP) (mouse monoclonal, clone GA-5, Biocare Medical) and synaptophysin (mouse monoclonal, clone 27G12, Biocare Medical). The gene discussed is GFAP; the disease is neoplasm.