Luis Requena, MD, is Professor of Dermatology and Chairman of the Department of Dermatology at Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain. He is also Visiting Professor of Dermatology at Wake Forest University and UCSF in the United States and at Graz University in Austria. Dr. Requena is a member of the Executive Committee of the International Society of Dermatopathology and a member of the Advisory Board and Examination Committee of the International Committee for Dermatopathology – European Union Medical Specialists. He is on the editorial boards of several leading journals and has won 40 national and international research prizes in Dermatology and Dermatopathology. He has trained more than 100 residents and fellows. He is the author of 420 papers in journals included in Med Line (Pub Med) as well as 93 chapters in textbooks. In addition he is the main author of 11 monographs. Omar P. Sangüeza, MD, is Director of Dermatopathology and Professor of Pathology and Dermatology at the Wake Forest University School of Medicine, Winston-Salem, NC, USA. He is also an Honorary Professor at the University of Montevideo, Uruguay. Dr. Sangüeza is a past president of the International Society of Dermatopathology and current president of the Sociedad Iberolatinoamericana de Dermatopatologia. He is also Editor-in-Chief of the American Journal of Dermatopathology. Dr. Sangüeza has received a number of awards, including the Walter R. Nickel Award from the American Society of Dermatopathology for Excellence in the Teaching of Dermatopathology. To date, he has trained around 70 national and international fellows. He is the author of 185 peer-reviewed journal articles as well as more than 15 book chapters and three books, including Pathology of Vascular Skin Lesions(Humana Press).