1. Department of Dermatology; Zealand University Hospital; Roskilde Denmark
2. Psoriasis Center; Department of Dermatology; University Medical Center Schleswig-Holstein; Campus Kiel Germany
3. Department of Dermatology; Hospital de la Santa Creu i Sant Pau; Universitat Autònoma de Barcelona; Barcelona Spain
4. Department of Dermatology and Allergy; Herlev and Gentofte Hospital; University of Copenhagen; Hellerup Denmark