This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal System, Subject name: Radiology
Onion peel appearance is seen in- 
Select and explain. 
A. Ewing's sarcoma, B. Chondroblastoma, C. Osteosarcoma, D. Fibrosarcoma
A: Ewing's sarcoma
Answer: A: Ewing's sarcoma 
Explanation: Ans. is 'a' i.e., Ewing's sarcoma * Onion - peel periosteal reaction is characteristically seen in Ewing's sarcoma.* Note - Onion peel periosteal reaction may also be seen rarely in osteosarcoma.Other Radiological features of Ewing's sarcoma* Diaphyseal* Mottled or moth eaten lesion* Sunray appearance (More common with osteosarcoma)* Codman's triangle (More common with osteosarcoma)