Background: Hydroxychloroquine is an antimalarial drug often used in dermatology for its photo-protective effects. Four cases of photodermatosis induced by hydroxychloroquine are reported.
Case reports: Four patients, aged from 21 to 68 years, developed a photolocalized eruption from 6 days to 10 weeks after starting hydroxychloroquine. The minimal erythemal dose was decreased in the total spectra and UVA at the onset of the eruption and became normal after stopping hydroxychloroquine in the 2 patients that were controlled. In 3 cases, hydroxychloroquine was the only single drug imputable; chronological imputability was plausible. In the last case, both hydroxychloroquine, carbamazepine and fluvoxamine had a common imputability which was plausible. In the 4 cases, a favourable outcome was observed after stopping hydroxychloroquine, and no recurrence occurred with a mean follow-up of 3.8 years (1-4 years). In one case, a photodistributed eruption occurred during treatment with a related molecule: chloroquine.
Discussion: Photodermatosis with hydroxychloroquine have rarely been described in the literature, while quinine from which hydroxychloroquine is derived, is well known for its risk of photosensibilization. The main differential diagnosis of these drug eruptions is an eruption caused by the photodermatosis that initially required treatment with hydroxychloroquine.