<prompt> A 40 years female presented with epiphyseal tumour at lower end radius. DiagnosisEwings sarcomaOsteogenic sarcomaGiant cell tumourChondromyxoid fibroma  <response>: i.e. Giant cell tumour: 216-J. Maheshwari 3rd Osteoclastoma Ginat cell tumour is located at the epiphysis old therapy Osteosarcoma and chondromyxoid fibroma are metaphyseal tumours while Ewings sarcoma is diphyseal The cells of origin is uncertain, Microscopically, the tumour consists of undifferentiated spindle cells, profusely interspersed with multinucleate giant cells. These giant cells were mistaken as osteoclasts in the past, hence the name Osteoclaustoma Giant cell tumour is a lesion of uncertain origin that appears in mature bone ApleyFeaturesOsteogenic SarcomaEwings sarcomaGiant cell tumourChondro-sarcomaAge years15-255-1520 - 40 i.e. after epiphyseal fusion30-60Common sitesLower end of femur, upper end of tibiaFemur, tibia, flat bones, multicentricLower femur, upper tibia, Lower radiusFlat bones upper end of femurLocationMetaphysisDiaphysis Endothelial cellsEpiphysis regionAny where in the boneClinical featuresPain swellingDuration-wks-monthPain,swellingDuration-wks-mths, often feverEpiphysis regionPain, swellingDuration-monthPain, swelling, Duration- mths-yearsX-ray picture Sunray appearance Codmans triangle Tumour new boneOnion-peel appearanceExpansile lesion,ccentric location Soap bubble appearanceMottled calcification within the tumourDifferential diagnosisEwings tumourOsteosarcomaOsteomyelitis No calcification within tumour MIC-2 is a specific markersAneurysmal bone cystFibrous dysplasiaOsteosarcoma Osteoclaustoma Chondroblastoma - Epiphysis Giant cell tumour of bone is now associated with over expression of osteoprotegerin ligand OPGL an important stimulator of osteoclast differentian, suggesting overactivity of osteoclast in the etiology of the neoplasm The benign giant cell tumour can later convert to a malignant condition such as osteosarcoma or malignant fibrous histiocytomaSite of origin of Primary bone neoplasmEpiphysisMetaphysisDiaphysis Chondroblastoma Giant cell tumour Osteosarcoma Chondroma Chondrosarcoma Osteoid osteoma Osteochondroma Brodies abscess not a tumour Ewings sarcoma Lymphoma Myeloma Adamantinoma Osteoid osteoma 