Actinic prurigo--a specific photodermatosis?

Actinic prurigo can be defined as an idiopathic photodermatosis which usually starts in childhood, particularly affects the female, with some evidence for an atopic and familial photosensitivity background. It affects both exposed and covered skin but mainly the former and although it may be present all the year round is usually maximal on the exposed skin during months of sunshine. The changes are those of a chronic prurigo along with more acute episodes following sunshine exposure in which there is a background of edematous erythema. It usually lasts throughout childhood and adolescence, but tends to wane and even to clear in late adolescence or early adult life. The etiology is unknown, as are the mechanisms involved. Action spectrum studies have produced no evidence for the involvement of specific wavelengths other than the presence of UV sensitivity in some subjects and a suggestion that the longer wavelength UVA may be more important than the sunburn waveband around 305 nm. Based on a study of 60 personal cases with actinic prurigo the authors agree with the longheld view of Calnan & Meara (1) that actinic prurigo is a separate and distinct photodermatosis.