One more clue of the expected dramatic outcome is the increased value of the Ki67 proliferation marker at immunohistochemistry analysis, as seen in the present case (20% to 80% depending on tumour area), which is similar to other reports of different sarcomas such as osteosarcomas or leiomyosarcomas [17,18,79,80]. This evidence concerns the gene MKI67 and osteosarcoma.