<prompt> Onion skin periosteal reaction is usually seen in:Ewings sarcomaOsteosarcomaWilms tumorOsteoblastoma  <response>: Ewing sarcoma Destructive lesion in the diaphysis of a long bone with an onion skin periosteal reaction. Originates in the metaphysis of a long bone, but frequently extends for a considerable distance into the diaphysis. Classically, PNET class of tumour, with c-myc positive,having round cells is histology. -Osteosarcoma show codmans triangle, sunray or sunburst appearance as periosteal reaction 