Conflicts of interest: G.C. has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. M.P. has received research funding from Almirall, Clinuvel and Pfizer; is an investigator for Allakos, Celldex Therapeutics, Escient, Incyte and Sanofi; has received consulting fees from Almirall, Galderma, Incyte and Sanofi; and has received speaker honoraria and/or travel fees from AbbVie, Beiersdorf, Celltrion, CSL Behring, Doctorflix, Eli Lilly, Falk Foundation, FomF GmbH, GA2LEN, Galderma, Novartis, P.G. Unna Academy, Sanofi, StreamedUP, TouchMDT and Zai Lab. S.S. was speaker and/or consultant and/or Investigator and/or has received research funding from Almirall S. A., Amgen Inc., Amgen Europe GmbH, Celldex Therapeutics Inc., Clexio Biosiences Ltd., Focus-Insight Healthtech Group Co. Ltd., Galderma Laboratorium GmbH, Galderma R&D LLC., Galderma S.A., GSK R&D Ltd., Incyte Corporation, Klirna Biotech Inc., Leo Pharma, Lilly Deutschland GmbH, Novartis Pharma GmbH, Sanofi-Aventis Deutschland GmbH, Sanofi-Aventis R&D, Sanofi Genzyme Corporation, TouchIME, Vifor Pharma Deutschland GmbH P. G. Unna Academy G.Y. serves as an advisory board member for AbbVie, Arcutis, Amgen, Celldex, GSK. Eli Lilly, Galderma, Kiniksa Pharmaceuticals, LEO Pharma, Novartis, Pfizer, Pierre Fabre, Maruho, Regeneron Pharmaceuticals, Inc., Sanofi, Clexio and Vifor. G.Y. receives grants/research funding from Sanofi, Sanofi Regeneron Novartis Pfizer, Escient, Celldex. G.Y. is an investigator for Galderma, Kiniksa, Amgen and Novartis.