This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Radiological finding of ewings sarcoma is: September 2005 
Select and explain. 
A. Soap bubble appearence, B. Sunray appearence, C. Onion peel appearence, D. Codman's triangle
C: Onion peel appearence
Answer: C: Onion peel appearence 
Explanation: Ans. C: Onion Peel Appearence Radiologically, Ewing's 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.