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: Radiology
[{'content': "Soft tissue mass in the chest with rib erosion in X-ray is seen in all except - \nSelect and explain. \nA. Leukemia, B. Ewing's sarcoma, C. Multiple myeloma, D. Osteosarcoma", 'role': 'user'}, {'content': "Answer: A \nExplanation: Multiple myeloma, Ewing's sarcoma and parosteal osteosarcoma can cause rib lesion with adjacent soft tissue mass.\nLeukemia does not cause rib lesion with adjacent soft tissue mass.", 'role': 'assistant'}]