This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Orthopaedics
[{'content': "All of the following are true about Ewing's sarcoma, EXCEPT \nSelect and explain. \nA. Responds well to radiotherapy, B. Grows in diaphysis of long bones, C. Common in 4th decade, D. Has onion peel appearance on radiograph", 'role': 'user'}, {'content': 'Answer: C \nExplanation: (C) Common in 4th decade # Ewing sarcoma, a highly malignant primary bone tumor.> The tumor is derived from red bone marrow.> Most frequently, it is observed in children and adolescents aged 4-15 years and rarely develops in adults older than 30 years.> Ewing sarcoma is the second most common malignant bone tumor in young patients, and it is the most lethal bone tumor.> Typically, the periosteal reaction and new bone formation with an onionskin appearance may suggest the diagnosis of E wing sarcoma.> It is highly radiosensitive and it melts like ice but only to recur at a later date.', 'role': 'assistant'}]