Vitamin D Supplementation in Polymorphic Light Eruption

Polymorphic light eruption (PLE) is a common photodermatosis with a high prevalence of approximately 11 to 21% in the population. Similar to lupus erythematosus (LE), an UV-inducible systemic autoimmune disease, PLE has a female preponderance with a mean onset in the second to third decade of life. PLE lesions are very itchy and typically appear on sun-exposed body sites in spring or early summer. The quality of life in patients with PLE is often severely disturbed, as evidenced by high levels of anxiety and depression. For prophylaxis besides conventional sunscreens, photo(chemo)therapy is effective in many cases, when administered over several weeks for hardening in early spring before the first natural sun exposure takes place. However, because prolonged treatment with UVB and/or photochemotherapy is potentially carcinogenic, the search for pathogenic mechanisms and new treatment options in PLE is ongoing. The exact pathogenesis of PLE is currently unknown but findings suggest an autoimmune-type background with resistance to UV-induced immune suppression and simultaneous immune reactions against skin photo-neoantigens. The investigators have recently found that PLE patients had significantly reduced 1,25-(OH)2-vitamin D3 serum levels (13-14ng/ml) compared to the normal population (\>30ng/ml). In addition, the investigators were able to demonstrate in an intra-individual half-body trial that topical administration of an immunostimulatory 1,25-(OH)2-vitamin-D3 analogue calcipotriol reduced PLE symptoms in an experimental study. In the proposed randomized double-blinded placebo-controlled trial the investigators attempt to study the effect of oral vitamin D3 supplementation (2 x 40.000 IE, given orally two weeks apart) on PLE symptoms.