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: Surgery
[{'content': 'Which of the following is not true about osteoid osteoma \nSelect and explain. \nA. Most common true benign tumor of bone, B. Occurs between 10 - 30 years of age, C. Lesion appears ill defined on x-ray with permeative margins, D. Bone scan shows increased uptake in the lesion', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer-C. Lesion appears ill defined on x-ray with permeative marginsOsteoid osteoma is the most common true benign tumor of the boneThe tumor occurs between 10-30 years of age and is more common in males.The diaphysis of long bones is involved, most common bone involved is the tibia followed by femurOn X-ray, there is a small radiolucent area (nidus) surrounded by dense sclerosis.X-ray, in some cases, show local sclerotic thickening of the shaft that may obscure the small central nidus within the area of rarefaction.', 'role': 'assistant'}]