Sinus and Surgical Endoscopic Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Clinical Research Development Unit, Ghaem Hospital, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Department of Otorhinolaryngology, Sinus and Surgical Endoscopic Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Allergy Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Department of Pathology, Mashhad Branch, Islamic Azad University of Medical Sciences, Mashhad, Iran. Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.