Meeting report: Vitiligo Global Issues Consensus Conference Workshop "Outcome measurement instruments" and Vitiligo International Symposium, Rome, Nov 30–Dec 3rd. (13th June 2017) - van Geel, Nanja; Boniface, Katia; Seneschal, Julien; Jacquemin, Clément; Speeckaert, Reinhart; Wolkerstorfer, Albert; Bekkenk, Marcel; Lommerts, Janny E.; Hamzavi, Iltefat; Pandya, Amit; Eleftheriadou, Viktoria; Ezzedine, Khaled; et al.