Smoking is an independent association of squamous metaplasia in Chinese nasal polyps

Nasal polyposis demonstrates histological features of epithelial remodeling and variable inflammatory cellular infiltration. We studied a large series of Chinese nasal polyp (NP) samples to characterize these histological features and their associations with clinical characteristics.

A detailed histological study of nasal polyposis was performed employing various histopathological techniques. A total of 153 intraoperative NP biopsies were analyzed histologically. Sections were examined under microscopy to determine the percentages of different types of inflammatory cells, and types of epithelial remodeling. Two systems of subtyping NPs based on inflammatory cell infiltration were assessed. These were correlated with patient characteristics.

Epithelial remodeling patterns include epithelial hyperplasia (87.8% of specimens), goblet cell hyperplasia (53.2%), and squamous metaplasia (44.6%). Smoking was a strong independent association of squamous metaplasia (adjusted odds ratio [OR] 9.9; 95% confidence interval [CI], 4.2 to 22.9; p < 0.01). The most common inflammatory cells were neutrophils (median of 12.8%) and CD8+ T cells (12.8%), followed by macrophages (11.0%), CD4+ T cells (9.7%), eosinophils (8.6%), and mast cells (7.6%). We defined 2 systems to classify NPs based on proportions of eosinophils and neutrophils. The majority of NP samples were neutrophilic. The first classification system has greater histological correlation. Based on the first classification, eosinophilic nasal polyposis was associated with epithelial hyperplasia (OR 3.7, p = 0.019) and goblet cell hyperplasia (OR 3.4, p < 0.001).

The majority of Chinese NPs are neutrophilic and epithelial hyperplasia is the most common pattern of epithelial remodeling. We show for the first time that smoking has a strong association with squamous metaplasia in nasal polyposis.