1. Department of Dermatology, Venereology and Allergology; University Medical Center Mannheim; Ruprecht-Karls-University of Heidelberg; Mannheim Germany
2. Division of Statistics; University Medical Center Mannheim; Ruprecht-Karls-University of Heidelberg; Mannheim Germany
3. Department of Dermatology and Venereology; University of Zurich; Zurich Switzerland
4. Department of Dermatology; Helios Clinic Krefeld; Krefeld Germany
5. Department of Pathology; Hôpital Henri-Mondor; Créteil France
6. Department of Pathology; AP-HP; Hôpital Saint Louis; Université Paris Diderot; Sorbonne Paris Cité; UMR-S 1165; F-75010 Paris France
7. Department of Dermatology; Hôpital Saint-Louis; Université Paris Diderot; Sorbonne Paris Cité; Inserm U976; 1 Avenue Claude Vellefaux 75010 Paris France
8. Department of Dermatology; University of Vienna; Vienna Austria
9. Dermatologic Clinic; Department of Medical Science; University of Torino; Torino Italy
10. Department of Dermatology; Johannes Wesling Klinikum; Minden Germany
11. Division of Pathological Anatomy; University of Florence; Florence Italy
12. Department of Dermatology; Leiden University Medical Center; Leiden the Netherlands