Changes of the Histological Features in Nasal Polyps

Abstract

Objective: Depending on the inflammatory cell infiltration, nasal polyps can be categorized as eosinophilic type or non-eosinophilic type. There is a geographical difference in the prevalence of a certain pathological type of polyp. More than 80% of polyps in Western people are the eosinophilic type, while this type is rarely found among Eastern people. The periodical change in the prevalence of histological types of polyps was evaluated in this study.

Method: Two hundred total patients, each confirmed to the polyp biopsy, were enrolled between 1993 and 2010. Specimens were fixed in formalin, then made to a paraffin block and H&E stained slide, which was reviewed by 2 authors. The number of eosinophils per high power field (HPF) and other cellular, epithelial, and stromal markers were reviewed.

Results: We compared the nasal polyp eosinophil count by periods, the average eosinophil count/HPF increased from 7.22 (±1.695) in 1993 to 20.44 (±3.635) in 2010 (P = .001). Eosinophilic polyp (showing over 5 eosinophils/HPF) increased significantly from 26% in 1993 to 52% in (P = .000 -> P < .001). Among other histologic markers, lymphocytes, basement membrane thickening, and gland hypertrophy showed significant difference.

Conclusion: After comparative studies between histopathologic findings of nasal polyps from 1993 and 2010 respectively, the percentage of eosinophilic nasal polyp, known to be rare among Asians, including Koreans, have increased significantly.