<prompt> Regarding Osteosarcoma which one is trueAffects people in 5th or 6th decadeOccurs due to proliferation of osteoclastLymphatic metastasis is most commonSunray appearance indicates new bone-formation  <response>: D Sun-ray appearance indicates new bone-formation In its classic intramedullary form, Osteosarcoma is a highly malignant tumour arising within the bone an spreading rapidly outwards to the periosteum and surrounding soft tissues. It is said to occur predominantly in children and adolescents. X-ray appearances are variable: hazy osteolytic areas may alternate with unusually dense osteoblastic areas. The endosteal margin is poorly defined. Often the cortex is breached and the tumour extends into the adjacent tissues; when this happens, streaks of new bone appear, radiating outwards from the cortex - the so-called sunburst effect. Where the tumour emerges from the cortex, reactive new bone forms at the angles of periosteal elevation Codmans triangle. While both the sunburst appearance and Codmans triangle are typical of osteosarcoma, they may occasionally be seen in other rapidly growing tumours. 