Persistent light reactivity from systemic quinine.

A 41-year-old black female with psoriasis developed photosensitivity and a Koebner reaction while receiving phototherapy. She had been receiving oral quinine intermittently for muscle cramps. Photobiological evaluation revealed a strongly positive photopatch test to quinine sulfate and a marked persistent reduction in the minimal erythema dose to solar-simulated radiation in the uninvolved skin. There were no abnormal reactions to UVA. The photosensitivity is still present 3 years after the withdrawal of quinine. These features are similar to those observed previously in persistent light reactors to topical photosensitizers.