Chronic actinic dermatitis.

Chronic actinic dermatitis (CAD) is one of the most frequently encountered photodermatoses in patients older than 50 years of age. It is characterized by persistent redness of the face and other exposed areas. CAD can become so severe that even nonexposed parts of the body develop eczematous lesions and the disease persists during winter. The diagnosis must be confirmed by phototests that show a broad action spectrum with low threshold doses. CAD must be differentiated from photocontact allergy and airborne dermatitis. The histopathologic features in the early stages are comparable to contact dermatitis, whereas in the later stages they may be those of pseudolymphoma. The most popular treatments are azathioprine and PUVA.