These findings are in line with the data of Tang et al., indicating that SOX9 is, together with RUNX2, involved in the emergence and development of DDCS [17] and that SOX9 immunostaining is a helpful therapeutic tool to distinguish chondrosarcoma from various small round cell tumors such as small cell osteosarcomas, non-Hodgkin lymphomas and Ewing/PNET (primitive neuroectodermal tumor) family tumors [18]. This evidence concerns the gene RUNX2 and small cell osteogenic sarcoma.