CD4 and chordoma: For the immune microenvironment of chordoma, CD4+T cells and macrophages were currently believed as the most abundant infiltration subsets of immune cells, a variety of cytokines and chemokines were high secretion and multiple immune checkpoints such as PD-1, PD-L1 and CTLA-4 were high expression there, which had important impact on tumor progression and patient prognosis.