<prompt> 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?Polymorphic light eruptionHydroa vacciniformeActinic prurigoPersistent light reaction  <response>: 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: Rooks Textbook of Dermatology, 8th Edition, Page 29.15 