<prompt> Most common primary bone tumour in adult bone is:Chondro sarcomaOsteogenic sarcomaAdmintinomaEwings sarcoma  <response>: osteogenic sarcoma 218-M 185-Appleys 8th Osteogenic sarcoma is highly malignant primary bone tumour - Common in Age 15-25 years Osteoid osteoma - is the commonest true benign tumour of the bone. 