Structural changes of the nasal mucosa in allergic and atrophic rhinitis

Abstract

Background: Allergic and atrophic forms of chronic rhinitis are common among the population, characterized by a chronic progressive course with a tendency toward increasing prevalence. Worldwide, allergic rhinitis affects approximately 10–40% of adults and 2–25% of children.¹ According to a study conducted in Mongolia, the prevalence of allergic rhinitis among adults in Ulaanbaatar was reported to be 23.6%, with an increasing trend anticipated in the future.² In allergic and atrophic rhinitis, structural alterations occur in the nasal mucosa, including disruption of the normal architecture of the pseudostratified epithelium and ciliated cells, accompanied by changes in goblet cell number and dysfunction of their activity, resulting in a complex pathological process. In otorhinolaryngology practice in Mongolia, there is a relative lack of studies investigating the ultrastructural changes of the nasal mucosa in allergic and atrophic rhinitis. Aim: To compare ultrastructural and histological changes of the nasal mucosa in allergic and atrophic rhinitis. Materials and Methods: Ethical approval was obtained from the Research Ethics Review Committee of the Mongolian National University of Medical Sciences at the meeting held on April 24, 2020 (Protocol No. 2020/З-04). Appropriate ethical permission was also obtained from the EMJJ ENT Hospital. Nasal mucosal tissue samples were collected from surgically resected specimens of patients aged 20–45 years diagnosed with allergic and atrophic rhinitis. The mucosal specimens were processed at the Institute of Biomedical Sciences of the Mongolian National University of Medical Sciences. Samples were fixed and dehydrated according to the protocol, coated with 100 Å gold, and examined using a scanning electron microscope (FEI Quanta FEG 250, USA). In addition, parafÏn blocks were prepared, sectioned at 4 μm thickness, stained with Hematoxylin and Eosin, and analyzed histologically. Results: In allergic rhinitis, the pseudostratified epithelium was relatively preserved; however, disorganization of ciliated cells, partial loss of cilia, and goblet cell hyperplasia were observed. In contrast, atrophic rhinitis showed epithelial thinning, near-complete loss of ciliated structures, glandular atrophy, and submucosal fibrosis. Conclusion: Allergic rhinitis is associated with relatively mild and predominantly functional mucosal alterations, whereas atrophic rhinitis demonstrates severe structural damage with irreversible impairment of mucosal protective function.