<prompt> 7 year old child presents with a lesion in upper tibia. X-ray shows radiolucent area with Codmans triangle and Sunray appearance. Diagnosis is :Ewings sarcomaOsteosarcomaOsteoid osteomaChondrosarcoma  <response>: Ans. is b i.e. Osteosarcoma Codmans triangle and sunray appearance is seen in both Osteosarcoma Ewings tumor, but the catch point is location of the tumor i.e. upper end of tibia.Osteosarcoma - most commonly involves long bone metaphyses, especially around the knee and at the proximal end of the humerus.Ewings sarcoma - most commonly involves the mid-diaphyseal region common bones are tibia, fibula clavicle etc. About age Apleys writes - Osteosarcoma is said to occur predominantly in children and adolescents.For differential diagnosis of bone tumors see Q.no. 153 of Nov. 2001 