<prompt> Onion - peel appea ranee is seen in -Ewings sarcomaOsteomaOsteosarcomaOsteoclastoma  <response>: Ans. is a i.e., Ewings sarcoma o Onion - peel periosteal reaction is characteristically seen in Ewings sarcoma.Note - Onion - peel periosteal reaction may also be seen rarely in osteosarcoma,o Codmans triangle is characteristically seen in osteosarcoma. It may also be seen in Ewings sarcoma and osteomyelitis. Characteristic radiological features of few bone tumorso Celery-stick appearanceEnchondromaso Coat-hanger appearanceOsteochondromao Codman tumor and chicken-wire calcificationChondroblastomao Double density sign on radionuclide scanOsteoid osteomao Nidus and sclerotic rimOstoid osteomao Driven snow appearancePindborg tumoro Fallen fragmentHinged fragment signSimple unicameral bone cysto Eggshell covering of expansile cortex over surface of lesionABCo Soap bubble appearance.ABCo Soap bubble appearance goes into cornersGCT Osteoclastomao Floating tooth signEosinophilic granuloma, adamantinomao Onion skin onion peel appearanceEwing sarcomao Skip lesionsOsteosarcoma, Ewings sarcomao SunraySunburst appearanceOsteosarcomao String sign to differentiate from myositis ossificansParosteal osteosarcomao Popcommottled calcificationChondrosarcomao Shepherds crook deformityFibrous dysplasia Codmans triangleOsteosarcoma, Ewing sarcomao Winking owl signMetastasis to pedicles of vertebrao Corduroyaccordian vertebravertical striationsVertebral hemangiomao Polka dot sign on CTVertebral hemangiomao Geographical skullEosinophilic granulomao Hole-within-a-hole lesionEosinophilic granuloma 