1. Department of Dermatology, Venereology and Allergology HELIOS St Elisabeth Hospital Oberhausen University Witten/Herdecke Witten Germany
2. Institute of Virology National Reference Center for Papilloma‐ and Polyomaviruses University of Cologne Cologne Germany
3. Institute of Pathology Mülheim an der Ruhr Germany
4. Department of Dermatology Medical Center University of Freiburg Freiburg Germany