Department of Dermatology, Rikshospitalet, Oslo University Hospital, Oslo, Norway; Correspondence to: Christoffer Aam Ingvaldsen, MD, PhD, Department of Dermatology, Rikshospitalet, Oslo University Hospital, Postboks 4950 Nydalen, Oslo 0424, Norway
Erling Undersrud, MD, DipDermpath (ICDP-UEMS)
Department of Pathology, Stavanger University Hospital, Stavanger, Norway
Jon Gottfred Andersen, MD
Department of Dermatology, Stavanger University Hospital, Stavanger, Norway