UV-A-provoked localized bullous pemphigoid.

A 71-year-old woman had noticed the development of blisters on her forehead 4 months before she was referred to our department. Treatment with oral corticosteroids resulted in complete healing, but new blisters subsequently developed on the face, neck and backs of the hands. After the possibility of phototoxic and photoallergic reactions, as well as an abnormal porphyrin profile, had been excluded, the diagnosis of bullous pemphigoid was made by histological and direct immunofluorescent examination. UV-A provocation on the upper arm produced lesions histologically and immunohistochemically typical of bullous pemphigoid. Of particular importance was the fact that the blisters were limited strictly to light-exposed skin areas.