CD99 and neuroblastoma: NuMYOD1 and numyogenin expression was restricted to RMS (Figure 1J; Figure2), CD99 was expressed at significant higher levels in PNET and a subpopulation of (embryonal) RMS (Figure 1I; Figure 2), whereas strong reactivity for GD2 was specific for neuroblastoma (Figure 1H; Figure 2), and a CD34hi CD45− phenotype was restricted to the hemangiopericytoma case studied (Figure 2).