The clinical spectrum of the persistent light reactor.

Eight patients had a chronic photodermatitis of five to 19 years' duration. The clinical and photobiological features were consistent with the pattern observed in persistent light reactors. Severity and clinical presentation, however, were quite variable, ranging from a few isolated papules to extensive lichenification involving the entire exposed skin. Three had positive photopatch tests to halogenated salicylanilides, while the remaining five reacted to musk ambrette. Exposure of the uninvolved skin to UV-B or solar-simulated radiation provoked abnormal delayed papular or infiltrated reactions. Histological evaluation of these reactions in three cases disclosed moderate to dense perivascular lymphocytic infiltrates with occasional eosinophils, focal exocytosis, and epidermal spongiosis. We conclude that persistent light reactivity associated with photoallergic contact dermatitis shows a spectrum of disease activity and photosensitivity. Recognition of the subtle forms of this disease is important.