Epithelial Squamous Metaplasia and Dysplasia in Inflammatory Nasal Polyps: An Observational Study.

Nasal polyposis (NP) is characterized by polypoid outgrowths of chronically inflamed respiratory mucosa. The presence of squamous metaplasia and dysplasia on the mucosal surface of nasal polyps (NPs) represents different manifestations of epithelial atypia. The aim of this investigation was to evaluate the presence of epithelial squamous metaplasia and dysplasia in ethmoidal NPs. This retrospective analysis of prospectively collected data involved 212 patients with NP undergoing endoscopic ethmoidectomy. To evaluate possible etiological factors for epithelial atypia, the patients in whom we histopathologically detected the presence of epithelial atypia were compared with patients with "normal" NPs in accordance with the following characteristics as found in the patients' medical records: gender, age, main symptoms, preoperative extent of sinus disease on computed tomography, atopic status, aspirin sensitivity, cigarette smoking, and occupational exposure to different noxious factors. Epithelial atypia were detected histopathologically in 44 (20.7%) NP patients, whereas features of "true" dysplasia were found in only 1 (0.5%) patient. The presence of atypia was more frequent in males than in females (P = .008). The association with aspirin-exacerbated respiratory disease and with long-term occupational exposure to different noxious chemicals, especially in workers exposed to salts of heavy metals, was more frequent in NP patients with epithelial atypia than in patients without atypia (P = .023; P = .006, respectively). Our results suggest epithelial atypia in NPs are associated with aspirin sensitivity and occupational exposure to different noxious chemicals. Although extremely rare, epithelial dysplasia may occasionally be noted in NPs, a fact potentially useful for both rhinologists and pathologists.