Abstract
Chronic actinic dermatitis is a photosensitive skin disease that most commonly affects elderly Caucasian males, but can also affect younger patients, particularly those with an atopic background. The clinical presentation is that of a recurrent dermatitis of the photo-exposed sites that can progress to a more lichenified and generalized appearance in the chronic phase. Investigation is best performed at specialist phototesting centers using monochromator phototesting and reveals broadband photosensitivity. Positive patch and/or photopatch testing to allergens is seen in approximately 75% of patients. The etiology of chronic actinic dermatitis has not yet been fully elucidated but a probable basis is that of delayed T-cell-mediated cellular hypersensitivity to an as yet unknown photo-induced antigen. The clinical treatment of chronic actinic dermatitis can be problematic and is focused around physical measures to prevent recurrent exacerbations and suppressive methods to limit the severity of such episodes. Immunosuppressants are often required and it is anticipated that future advances in molecular biology will allow the pathogenesis of the disease to be further understood, thereby facilitating more targeted treatment approaches.