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What is Actinic prurigo and explain in detail?
Actinic prurigo is a  rare sunlight-induced, pruritic, papular or nodular skin eruption. Some medical experts use the term actinic prurigo to denote a rare photodermatosis that develops in childhood and is chronic and persistent; this rare photodermatosis, associated with the human leukocyte antigen HLA-DR4, is often called "Familial polymorphous light eruption of American Indians" or "Hereditary polymorphous light eruption of American Indians" but some experts consider it to be a variant of the syndrome known as polymorphous light eruption (PMLE). Some experts use the term actinic prurigo for Hutchinsons summer prurigo (aka hydroa aestivale) and several other photodermatoses that might, or might not, be distinct clinical entities.

Symptoms
AP is characterized by itchy, inflamed papules, nodules, and plaques on the skin. Lesions typically appear hours or days after exposure of the skin to UV light, and follow a general pattern of sun-exposed areas