Actinic prurigo.

Actinic prurigo is a chronic photodermatitis found predominantly in North American Indians. Other terms have been used to describe similar cases in Central and South America and in Europe. Relatively little has been written about this condition in the English literature, and confusion exists over whether this is a form of polymorphic light eruption. Actinic prurigo can be considered a unique variant of polymorphic light eruption; however, we believe that certain differences help to distinguish actinic prurigo as a separate disease entity. Herein we report three cases of this disease and review the related literature. Characteristic clinical features include prurigolike papules and cheilitis. Pruritus is the predominant symptom, and a familial tendency and an early age at onset are usually noted. Results of karyotyping and analysis of sister chromatid exchanges were normal in two of our patients so tested. Skin testing for photosensitivity has yielded inconsistent results, and use of light testing for diagnosing actinic prurigo does not seem to be a predictable procedure. Actinic prurigo is a chronic disease that often is refractory to therapy.