1 Department of Dermatology, Allergology and Venerology, International Centre for Acne Inversa/Hidradenitis Suppurativa (ICH), Ruhr-University Bochum, Bochum, Germany.
2 Department of Plastic, Reconstructive and Aesthetic Surgery, Essen-Mitte Hospital, Essen, Germany.
3 Department of Dermatology, Karolinska Institutet Stockholm, Stockholm, Sweden.
4 Department of Plastic and Reconstructive Surgery, BG University Hospital Bergmannsheil Bochum, Ruhr-University Bochum, Bochum, Germany.