Time period between occurrence of osteosarcoma following radiation therapy:

D i.e. 10 yearsRef: Diagnostic Pathology: Bone, By G. Petur Nielsen, Andrew E Rosenberg, 2nd edition, pageExplanation:Post-radiation OsteosarcomaLatent period from radiation is long: Median 11 years.Rarely as little as 2 years.Latency inversely related to radiation dose.OsteosarcomaThe 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 (Codman's triangle).While both the sunburst appearance and Codman's triangle are typical of osteosarcoma, they may occasionally be seen in other rapidly growing tumours.Risk Factors for OsteosarcomaFamilial cases where the deletion of chromosome '13q14' inactivates the retinoblastoma gene is associated with a high risk of osteosarcoma development.Bone dysplasias, including Paget's disease, fibrous dysplasia, enchondromatosis, and hereditary multiple exostoses, increase the risk of osteosarcoma.Li-Fraumeni syndrome (germline TP53 mutation) is a predisposing factor for osteosarcoma development.Rothmund-Thomson syndrome (i.e., autosomal recessive association of congenital bone defects, hair and skin dysplasias, hypogonadism and cataracts) is associated with increased risk of this disease.Bone irradiation.Note:Characteristic histologic finding of osteosarcoma:Bone forming tumor (osteo = bone).Presence of osteoid.Characteristic radiologic features:Codman's triangle.Sunburst appearance.