1 Department of Dermatology, Allergology and Venereology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Consultation "tatouages", service de dermatologie, hôpital Bichat, Claude-Bernard, AP-HP, Paris, France. Electronic address: nicolas.kluger@hus.fi.
2 Department of Dermatology, Allergology and Venereology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
3 Ylioppilaiden Terveydenhoitosäätiö YTHS (Foundation for Student Health), Helsinki, Finland.