The myeloid compartment of Ewing sarcoma was composed of mast cells, a small fraction of plasmacytoid dendritic cells (pDC), type 1 and type 2 conventional dendritic cells (cDC1, cDC2), undifferentiated macrophages (Mo), and four differentiated macrophage subsets (FAPB4+, CCL3+, APOElow, and GPNMB+ Mφ; Table 1; Fig. 2A and 3A). Here, CCL3 is linked to Ewing sarcoma.