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: Skin
[{'content': 'A 12 year old boy after spending his holiday in a Kovalam beach develops pruritic haemorrhagic vesicles on cheeks, ears, nose and hands after 12 hours. A week later the lesions crusted and healed with permanent scars. What is the most probable diagnosis? \nSelect and explain. \nA. Polymorphic light eruption, B. Hydroa vacciniforme, C. Actinic prurigo, D. Persistent light reaction', 'role': 'user'}, {'content': "Answer: B \nExplanation: All these are acquired autoimmune photodermatoses of which hydroa vacciniforme presents typically in the 1st decade of life with haemmorhagic vesicles healing with scars. Ref: Rook's Textbook of Dermatology, 8th Edition, Page 29.15", 'role': 'assistant'}]