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: Dental
[{'content': 'A 12-year-old boy had a gradually progressive plaque on a buttock for the last 3 years. The plaque was 15 cm in diameter, annular in shape, with crusting and induration at the periphery and scarring at the centre. The most likely diagnosis – \nSelect and explain. \nA. Tinea corporis, B. Granuloma annulare, C. Lupus vulgaris, D. Borderline leprosy', 'role': 'user'}, {'content': 'Answer: C \nExplanation: This boy has\n\n\nAnnular plaque\nOn buttock\nCrusting at periphery\nScarring at centre\n\nThese suggest the diagnosis of lupus vulgaris.\nAnnular lesions\xa0\n\nWhen the lesions of a skin disease are arranged in ring shape, they are called annular lesions.', 'role': 'assistant'}]