Persistent light reaction with erythroderma caused by musk ambrette: a case report.

Persistent light reaction is an uncommon type of photodermatitis caused mainly by musk ambrette, a synthetic fragrance material commonly used in foods and cosmetics. Erythrodermic persistent light reaction is rare. We report a case of erythroderma with underlying persistent light reaction due to musk ambrette. A 71-year-old man showed a photodermatitis that waxed and waned for five years before it became more persistent and finally evolved into erythroderma. Positive results of a photopatch test to musk ambrette and a low minimal erythema dose to ultraviolet B were noted. A biopsy specimen of the erythrodermic lesion revealed spongiotic dermatitis. The erythroderma and photodermatitis responded to systemic steroids and psoralen/ultraviolet A therapy (total dose: 90 J/cm2). We suggest that persistent light reaction be included in the differential diagnosis of erythroderma.