1. Information Network of Departments of Dermatology (IVDK)/Univ.‐Hautklinik, von Siebold Str. 3, D‐37075 Göttingen, Germany,
2. Department of Dermatology, University of Osnabrück, Germany,
3. Department of Dermatology, Dortmund/University of Witten‐Herdecke, Germany