Etiology:
1. Microenvironment theory of middle nasal meatus
The microenvironment gap of middle nasal meatus is narrow and uneven, and the inhaled airflow is easy to form turbulence here. Ciliary function is weakened and ciliary activity is damaged; The mucosal blood flow of middle nasal meatus was significantly lower than that of other parts of nose. The natural defense function of middle nasal meatus is weakened, and it is easily damaged by harmful factors locally, which creates conditions for the formation of nasal polyps.
2. Nasal allergy
Many mast cells, eosinophils and IgE-producing cells can be seen in nasal polyps, and the level of IgE in their fluid is increased, suggesting that local allergy has a certain effect.
3. Eosinophilic inflammation
Nearly 90% of nasal polyps have more eosinophil infiltration, suggesting that nasal polyps are closely related to eosinophilia.
4. Bacterial superantigen theory
Staphylococcus aureus is one of the common bacteria in nasal cavity. Staphylococcus aureus enterotoxin can directly activate a large number of Th2 cells, B cells, eosinophils and mast cells in the nasal mucosa of the middle nasal meatus, so that they can synthesize and release a large number of pro-inflammatory cytokines, aggravate the local inflammatory reaction of the middle nasal meatus and promote the formation of polyps.