CD274 and synovial sarcoma: Total gluco-sides of paeony (TGP), which may increase the expression of PD-1 and its relevant ligand PD-L1 in the peripheral blood mononuclear cells, may play a role in the pathogenesis and development of SS through the PD-1/PD-L1 pathway, by regulating regulatory T cells/T helper cell 17.19