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': 'True about synovial chondromatosis is? \nSelect and explain. \nA. Elderly men are affected, B. Bone scan is usually normal, C. Metaplastic cartilage formation occurs throughout the synovium, D. Chondrosarcoma is a common complication', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans CPrimary synovial chondromatosis is a type of non-cancerous monoarticular lesion of unknown etiology that arises from synovial metaplasia of a joint. The knee is most commonly affected, however it can affect any joint. The tumors begin as small nodules of cartilage of similar sizes. These nodules can separate and become loose within the joint. Synovial chondromatosis most commonly occurs in adults ages 20 to 50. Treatment may involve surgery to remove the lesions. Recurrence is common.', 'role': 'assistant'}]