<prompt> Radiological finding of ewings sarcoma is: September 2005Soap bubble appearenceSunray appearenceOnion peel appearenceCodmans triangle  <response>: Ans. C: Onion Peel Appearence Radiologically, Ewings sarcoma is often associated with a lamellated or onion skin periosteal reaction. This appearance is caused by and splitting and thickening of the coex by tumor cells. The lesion is usually lytic and central. Endosteal scalloping is often present. The onion-skin appearance is often followed with a moth-eaten or mottled appearance and extension into soft tissue. Bone marrow infiltration is not obvious on plain x-ray. 