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: Unknown
[{'content': 'A 56-year old man presented with bony pain.  X-ray skull lateral view shows: \nSelect and explain. \nA. Pagets disease, B. Hyper osteosis frontalis, C. Fibrous dysplasia, D. Osteopetrosis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ref. Grainger and Allison's Diagnostic Radiology. Page. 483\n\xa0\nPagets disease of bone affects each person differently . It includes :\n1 Bones : Pain in the affected bones is the most common symptom of pagets disease of bone.\n\xa0 Skull in Pagets disease \n\nosteoporosis circumscripta: large, well-defined lytic lesion\ncotton wool appearance:\xa0mixed lytic and sclerotic lesions of the skull\ndiploic widening: both inner and outer calvarial tables are involved, with the former usually more extensively affected\nTam o'Shanter sign: frontal bone enlargement, with the appearance of the skull falling over the facial bones, like a Tam o' Shanter hat", 'role': 'assistant'}]