This is clinically distinct from a polymorphic light eruption although its unknown cause may be the same. Papules, crusts and excoriations arise on sun-exposed areas and sometimes also on other sites. Lesions may persist through the winter. It is common among North American Indians and may resemble excoriated acne, bites, eczema, erythropoetic protoporphyria or neur-otic excoriations. It may be associated with atopy.