Eosinophilic allergic polyp: a clinically oriented concept of nasal polyp.

Abstract

Tissue eosinophilia is a hallmark of nasal polyposis. However, there is no universally accepted definition for eosinophilic nasal polyp. The aims of this study were to histologically analyze the inflammatory cell population in the nasal polyp and propose the concept of eosinophilic allergic polyp (EAP), a simple and objective concept that would be clinically and practically valuable. A cohort study with histological analysis of tissue sections and chart review. A tertiary university hospital. Nasal polyp tissues were harvested during routine endoscopic sinus surgery from a cohort of 118 patients. Total number of inflammatory cells, including eosinophils, was counted. The presence of allergy and asthma was assessed, which was then correlated with the histologic findings. To determine a criterion for EAP, a receiver operating characteristic curve was used to identify the best cutoff point, which was further validated by comparing the eosinophil proportion in each group with reference to the clinical parameters. Eosinophil accounted for an average of 18.7% of all inflammatory cells. The proportion of nasal polyps with at least 1 or more eosinophil infiltration accounted for 90.7% of all nasal polyps. When the concept of EAP was applied, a tissue eosinophil count of 11% was found to be significant and clinically most useful. Using this criterion, the proportion of EAP among nasal polyps was 62.7%. The authors suggest a tissue eosinophil proportion of more than 11% as a criterion for EAP, a clinically useful concept of nasal polyp that bears good correlation with asthma and allergy.