Purpose of review: Nasal polyps is a common ENT disease with high medical failure and recurrence rate, reflecting unknown pathogenesis. The present review is an update on the etiopathogenesis of nasal polyps.
Recent finding: Several mechanisms have been proposed for the formation of nasal polyps, including allergy, mucosal allergy, autonomic imbalance, nitric oxide, superantigens, infection, abnormal transepithelial ion transport, mucopolysaccharide abnormality, mechanical obstruction and epithelial rupture. Eosinophils comprises more than 60% of the cell population. Activated T cells, mast cells and plasma cells are also increased compared with the normal nasal mucosa. The stroma has numerous mediators, including cytokines, growth factors, adhesion molecules, and immunoglobulins. Both Th1 and Th2 types of cytokines are upregulated independent of the atopic status. An increased production of GM-CSF, IL5, RANTES and eotaxin can contribute to chronic eosinophilic inflammation by regulating the migration, survival and activation of eosinophils.
Conclusion: Nasal polyps is a multifactorial disease, with infectious, noninfectious, inflammation, anatomic and genetic abnormalities. Chronic inflammation remains the central major factor in nasal polyps.

Keywords: Nasal polyps, Etiology, Pathogenesis, Histology