Zubair W. Baloch, MD, PhD is Professor of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania Medical Center, Philadelphia, PA, USA. Tarik M. Elsheikh, MD works at the Robert J. Tomsich Pathology and Laboratory Medicine Institute, Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH, USA. William C. Faquin, MD, PhD is Director of Head and Neck Pathology, Massachusetts General Hospital and Massachusetts Eye and Ear Infirmary, and Associate Professor of Pathology, Harvard Medical School, Boston, MA, USA. Philippe Vielh, MD, PhD works at the Department of Pathology, Institut Gustav Roussy, Villejuif, France.