Figure 15. Radiograph shows a mixed lytic and sclerotic lesion with punctate calcifications (arrow) and with evidence of cartilage matrix inferiorly. In addition, there is a denser region of amorphous mineralization superiorly (arrowhead) with features that are more suggestive of osteoid matrix. Pathologic examination revealed a grade 4 osteosarcoma arising within a grade 1 chondrosarcoma.