A rapid regeneration of the epithelium takes place in the maxillary sinus in rabbits after experimental operative removal of the mucosa. Two weeks postoperatively the previously denuded areas have reepithelialized. The subepithelial glands, however, do not seem to regenerate. The normal sinus mucosa contains numerous serous glands in the lamina propria, but in the regenerated mucosa these glands are replaced by dense connective tissue. Atypical glands and polyp formations are sometimes encountered, but goblet cells are sparse. Furthermore, the sinus cavity on the operated side is reduced in size compared with the nonoperated side because of fibrosis and periosteal reactions including bone degradation and neogenesis. This study indicates that although the mucosa is reepithelialized within 2 weeks, the regeneration of the lamina propria is incomplete, and reactive cellular processes such as bone remodeling, fibroblast proliferation, and formation of polyps and "atypical glands" are characteristic of regenerating mucosa.

The aim of the present investigation was to study the histopathologic mucosal changes occurring in chronic maxillary sinusitis both preoperative and postoperative to functional endoscopic sinus (FES) surgery and the Caldwell-Luc (C-L) operation. Correlations were also sought between the histopathologic parameters and endoscopic findings, as well as patient symptoms. Sixty sinuses with the FES surgery and 55 sinuses with the C-L procedure were studied. The histologic parameters were graded semiquantitatively and compared preoperatively and postoperatively. The C-L operation reduced almost all parameters, whereas after the FES operation only edema and inflammatory cells were significantly reduced. Fibrosis increased postoperatively with both methods. The number of inflammatory cells was closely correlated to a thickened antral mucosa and to purulent secretion. No valid correlations were found when comparing histology with patient symptoms. All in all, histologic considerations suggest that asthmatic patients with severe sinonasal polyposis might benefit from the C-L procedure.

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In the present investigation, the regenerative capacity of the infected maxillary sinus mucosa following surgical procedures was studied in a rabbit model. Sinusitis was induced by occluding the ostium with and without the addition of Staphylococcus aureus or Bacteroides fragilis, or by provoking a prolonged bacterial infection with both pathogens. The surgical procedures performed were 1) widening of the natural sinus ostium (middle meatal antrostomy; MMA) and 2) removal of sinus mucosa without ostial interference (modified radical operation; MRO). The histologic features of the entire nose-sinus complex were studied, graded semiquantitatively, and compared with findings in untreated sinusitis, or after surgery only. Whereas MMA and MRO both led to a decrease of the inflammatory features of the sinus mucosa in induced sinusitis, persistent local histopathology was observed in the ostial region following MMA surgery. This indicates the importance of local pathologic changes resulting from interactions of bacterial colonization, inflammation, and surgery in chronic sinusitis.