PDCD1LG2 and chondrosarcoma: In our study, a significant association was observed between expression of the combined PD-1 ligands and expression of PD-1 not only in sarcomas as a whole but also in osteosarcoma, synovial sarcoma, and chondrosarcoma, which indicates that PD-L1 and PD-L2 should be regarded as a whole for systematic investigations.