Imaging features of osteosarcoma. Panel A is a plain radiograph demonstrating a lytic destructive lesion with malignant new bone formation involving the medial aspect of left distal femur. Panel B is a coronal CT image showing typical periosteal new bone formation with cortical destruction associated with a lytic bony lesion involving the left distal femur. Panel C is an enhanced MR image demonstrating an eccentric left distal femoral metaphyseal mass with a large extra-osseous component. Panel D is an axial image of a CT-guided biopsy sampling of the extra-osseous mass. Panel E is an image from a thallium bone study showing uptake overlying the distal left femur indicative of high grade tumour at this site.