Squamous and Respiratory Metaplasia After Olfactory Mucosal Resection

Abstract

Resection of the olfactory mucosa (OM) is sometimes unavoidable during surgery; however, it is not known whether the OM can completely recover thereafter. The aim of this study was to uncover whether the OM fully recovers after mucosal resection and describe the process of OM regeneration. 8-week-old male Sprague–Dawley rats (n = 18) were subjected to OM resection at the nasal septum; six rats were euthanized for histological examination 0, 30, and 90 days after surgery. Immunohistochemistry was performed to identify olfactory receptor neuron (ORN) lineage cells [mature and immature ORNs and ORN progenitors, and olfactory ensheathing cells (OECs)], as well as dividing and apoptotic cells. Squamous and respiratory metaplasia and inflammatory cell infiltration were also assessed. On day 30 after resection, the mucosa had regenerated, and mainly contained thin nerve bundles, basal cells, and immature ORNs, with a few mature ORNs and OECs. On day 90, the repaired nasal mucosa had degenerated into stratified squamous or ciliated pseudostratified columnar epithelia, with reducing ORNs. The lamina propria contained numerous macrophages. Partial regeneration was observed within 1 month after OM resection, whereas subsequent degeneration into squamous and respiratory epithelia occurred within 3 months. Given the poor persistence of ORNs and OECs, OM resection is likely to result in olfactory impairment. Overall, surgeons should be cautious not to injure the OM during surgery.

Olfactory Loss in Rhinosinusitis: Mechanisms of Loss and Recovery

“…The authors observed regeneration of the OE after 30 days followed by its degeneration into squamous or ciliated epithelia after 90 days with presence of connective tissue [82]. Furthermore, the influx of macrophages in the tissue was higher after 90 days than after 30 days, questioning the role of inflammation in metaplasia [82]. This OE metaplasia was also shown in a rat lesioned OE.…”

“…Results also showed differences in the number of normal OSNs with 24% in CRS patients compared to 45% in healthy controls as well as a more severe erosion of the OE in CRS patients [81]. A more recent study observed OE regeneration after surgical lesion of rat OE [82]. Resections of the olfactory mucosa present on the nasal septum were analysed by immunohistochemistry at 0, 30, and 90 days after surgery.…”

“…Resections of the olfactory mucosa present on the nasal septum were analysed by immunohistochemistry at 0, 30, and 90 days after surgery. The authors observed regeneration of the OE after 30 days followed by its degeneration into squamous or ciliated epithelia after 90 days with presence of connective tissue [82]. Furthermore, the influx of macrophages in the tissue was higher after 90 days than after 30 days, questioning the role of inflammation in metaplasia [82].…”