1. Department of Otorhinolaryngology and Head and Neck Surgery, Erasmus MC Cancer Institute, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
2. Department of Pathology, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
3. Department of Pathology, Antwerp University Hospital, Drie Eikenstraat 655, B-2650 Edegem, Belgium
4. Faculty of Medicine, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium