Development of chronic actinic dermatitis in a patient with atopic dermatitis: a case report and a review of reported cases.

A 30-year-old Japanese woman who had suffered from atopic dermatitis (AD) since childhood was referred for the evaluation of itchy erythema in sun-exposed regions, which persisted for 3 years. Phototesting revealed that the minimal erythema dose (MED) to ultraviolet (UV)B radiation was 20 mJ cm-2 and MED to UVA radiation was 10 J cm-2. Phototesting with visible light revealed no positive reaction. The skin lesion was diagnosed as chronic actinic dermatitis (CAD). She was asked to strictly avoid exposure to sunlight; thereafter, her skin symptoms disappeared. There have been 18 reported cases of CAD developing in patients with AD, including our patient. Interestingly, CAD appeared before the age of 30 years in 15 of the 18 cases, suggesting that the age of onset of CAD in patients with AD may be younger than that in typical patients with CAD. Accordingly, we recommend performing phototesting on patients with AD with features of photoaggravated dermatitis to diagnose photosensitivity and provide appropriate management.