<prompt> Codmans triangle is seen in -OsteosarcomaOsteoblastomaOsteoclastomaGCT  <response>: Ans. is a i.e., Osteosarcoma o Codmanrs triangle and sun ray appearance are typical of osteosarcoma.o However, you should keep in your mind following very important facts : -Sunray sunburst appearance and codmans triangle indicates periosteal reaction periosteal new bone formation,Both these are typical of osteosarcoma but may also occur in other rapidly growing bone tumors Ewings sarcoma, and infection osteomyelitis.Similarly, onion peel appearance indicates periosteal new bone-formation and is typical for Ewings sarcoma. But this can also occur in oseosarcoma and osteomyelitis.The crux is that, aggresivelv growing tumors and infection stimulate the periosteum which then react by forming new bone, therefore it is called periosteal reaction which may take any of the above form.o Sun-ray sunburst appearance and Codmans triangle: -Typical features of osteosarcoma,May also be seen in Ewings sarcoma. osteomyelitis,o Onion-peel appearanceTypical feature of Ewings sarcoma.May also be seen in osteosarcoma, and osteomyelitis 