GFAP and myeloid sarcoma: Co‐staining for cell phenotype markers showed that the percentage of CD1d‐positive cells showing immunoreactivity for GFAP was significantly higher in MS than in the control tissue, (72.57 ± 14.45% CD1d+GFAP+ vs. 30.33 ± 20.22% CD1d+GFAP+, respectively; P ≤ 0.0001) (Figure 4A).