CD68 and chordoma: To identify myeloid cells within the chordoma tumor microenvironment, chordoma tissue sections were stained using an automated multispectral immunofluorescence system with antibodies against C11b, HLA-DR, CD14, CD15, CD68, and cytokeratin (CK) (Figure 1A) followed by digital scanning, image annotation, and cellular analysis (Supplementary Figure 1).