1. Departments of Dermatology, Free University Hospital of Amsterdam, The Netherlands
2. Pathology, Free University Hospital of Amsterdam, The Netherlands
3. Epidemiology and Biostatistics, Free University Hospital of Amsterdam, The Netherlands
4. Department of Pathology, University Hospital of Utrecht, The Netherlands
5. Department of Pathology, University Hospital of Groningen, The Netherlands
6. Department of Dermatology, University Hospital of Gent, Belgium