Nasal polyps are benign, often bilateral sessile or pedunculated semitranslucent mucosal outgrowths of the nasal cavity and paranasal sinuses. They occur in 1%-4% of the general population, with peak incidence in individuals between the ages of 20 and 40 years.

The majority of cases are associated with edema and eosinophilic infiltration. Although the precise cause of formation is unknown, the etiology of nasal polyps is regarded as multifactorial and as being linked with chronic mucosal inflammation. Contributing factors may include cytokine mediators, innate immune defects, infection, genetic factors, environmental exposures, and inflammatory conditions.

Nasal polyps are frequently associated with chronic sinusitis, asthma, aspirin sensitivity, nonallergic (eg, vasomotor, drug induced) and allergic rhinitis and rhinosinusitis, cystic fibrosis, and alcohol intolerance.