β£Description of OsteosarcomaL - metaphysealA - blasticR - wide zone, periosteal reaction - Codman's triangle, extension into soft tissueM - osteoid matrixβ£What are the types of Osteosarcoma?Primary or SecondaryPrimary -Within bone - intramedullary (95%)On surface of boneParosteal (low grade and spares medullary canal),Periosteal (intermediate grade surface OS),High grade surface OS,TelangiectaticSecondary - paget's disease, post radiationβ£Commonest sites?Areas with high bone turnover - distal femur, proximal tibia, proximal humerusβ£What are the genes associated with Osteosarcoma?Tumor suppressor gene retinoblastoma (Rb)p53 gene (Li Fraumeni syndrome)Rothmund Thomson Syndromeβ£What grade is it usually at diagnosis?2B = high grade, Extra-compartmentβ£What are the poor prognostic factors for osteosarcoma? Blood tests - ALP (higher ALP has lower overall survival), LDH (higher LDH lower overall survival)Imaging factors (2) - skip lesion, pathological fractureHistological features (3) - of vascular invasion, tumor grading, expression of P glycoproteinChemo response (1) - Poor response to chemo as defined as tumor necrosis aka kill rate > 90% as assessed on repeat MRI or PET scanβ£Any impact on prognosis if there is a pathological fracture?5 year survival rate reducedIncreased risk of local recurrenceNo difference in lumb salvage vs amputation.β£Hallmark of histology in osteosarcoma?1. Lacey disorganized Osteoid2. spindle cells, 3. malignant stromal cellsβ£Management of osteosarcoma?Neoadjuvant chemo x 6/52 about 3 courses to kill micromets and sterilize reactive zoneRepeat MRI to evaluate tumor necrosisSurgery - salvage vs amputationβ£Response to Radio/ Chemo?Radioresistant