1. Department of Dermatology; Medical Center, University of Freiburg; Hauptstrasse 7 Freiburg 79104 Germany
2. Department of Paediatric Dermatology; University Children's Hospital Zurich; University Hospital Zurich; Zurich Switzerland
3. Department of Dermatology; University Children's Hospital Zurich; University Hospital Zurich; Zurich Switzerland
4. Department of Dermatology; University Hospital Bern; Bern Switzerland