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
[{'content': "MARTEL'S sign is seen in \nSelect and explain. \nA. Gout, B. SLE, C. Takayasu, D. Kawasaki disease", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. GoutCystic changes, well-defined erosions with sclerotic margins (often with overhanging bony edges), and soft tissue masses are characteristic radiographic features of advanced chronic tophaceous gout. Martel sign sharply marginated bony erosions from a long standing soft tissue tophus in patient with gout.', 'role': 'assistant'}]