1 Department of Dermatology (Grijsen), Leiden University Medical Center, Leiden; Department of Dermatology (de Vries), Academic Medical Center, University of Amsterdam; STI Outpatient Clinic (de Vries), Public Health Service Amsterdam, Amsterdam, The Netherlands m.l.grijsen@lumc.nl.
2 Department of Dermatology (Grijsen), Leiden University Medical Center, Leiden; Department of Dermatology (de Vries), Academic Medical Center, University of Amsterdam; STI Outpatient Clinic (de Vries), Public Health Service Amsterdam, Amsterdam, The Netherlands.