Solar Urticaria

Abstract

Solar urticaria is a disease in which a person develops hives during or immediately after exposure to nonionizing electromagnetic radiation contained in the solar spectrum. The urticaria is restricted to the site of exposure, but systemic symptoms such as headache and malaise can accompany it. Solar urticaria was first described as a distinct clinical entity in 1905 by Ward,¹ who reported the case of a woman who developed an urticarial reaction and associated systemic symptoms following exposure to sunlight. By conducting some simple tests, he found that the reaction in this patient was triggered by exposure to UVA radiation and that other physical stimuli such as cold, heat, and X rays did not reproduce the reaction. The name solar urticaria was coined by Duke² in 1923, when he described another case and compared solar urticaria to urticarial reactions precipitated by other physical stimuli. Since those early reports, many cases of solar urticaria have been described and a large body of literature on its photobiologic aspects has been published. A few studies have been made of the possible immunologic features of the disease and the results suggest that, in some cases, the pathogenesis may involve an interaction between nonionizing radiation and the immune system.