1. Second Dermatology Department, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
2. Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London WC1H 9SH, UK
3. Dermatology Department, Pius Hospital de Valls, Universidad de Alacalá, 43800 Valls, Spain