Randomized double-blinded placebo-controlled intra-individual trial on topical treatment with a 1,25-dihydroxyvitamin D₃ analogue in polymorphic light eruption.

BACKGROUND: Polymorphic light eruption (PLE) is a very frequent photodermatosis whose pathogenesis may involve resistance to ultraviolet (UV)-induced immune suppression. Similar to UV radiation, calcitriol (1,25-dihydroxyvitamin D₃) and its analogues such as calcipotriol have been shown to exhibit immunosuppressive properties.

OBJECTIVES: We performed a randomized double-blinded placebo-controlled intraindividual half-body trial (NCT00871052) to investigate the preventive effect of a calcipotriol-containing cream in PLE.

METHODS: Thirteen patients with PLE (10 women, three men; mean age 37 years) pretreated their skin on two symmetrically located test fields with calcipotriol or placebo cream twice daily for 7 days before the start of photoprovocation testing with solar-simulated UV radiation. We established a specific PLE test score [AA + SI + 0·4 P (range 0-12), where AA is affected area score (range 0-4), SI is skin infiltration score (range 0-4) and P is pruritus score on a visual analogue scale (range 0-10)] to quantify PLE severity.

RESULTS: Photoprovocation led to PLE lesions in 12/13 (92%) patients. As shown by the PLE test score, compared with placebo calcipotrial pretreatment significantly reduced PLE symptoms in average by 32% (95% confidence interval 21-44%; P = 0·0022, exact Wilcoxon signed-rank test) throughout the observation period starting at 48 h until 144 h after the first photoprovocation exposure. At 48, 72 and 144 h calcipotriol pretreatment resulted in a lower PLE test score in 7 (58%), 9 (75%) and 10 (83%) of the 12 cases, respectively. Considering all time points together, calcipotriol diminished the PLE test score in all 12 photoprovocable patients (P = 0·0005; Wilcoxon signed-rank test).

CONCLUSIONS: These results suggest a potential therapeutic benefit of topical 1,25-dihydroxyvitamin D₃ analogues as prophylactic treatment in patients with PLE.