aetiology

Last reviewed 01/2018

The cause of nasal polyps is not fully understood. It is probably multifactorial including allergy, infection and mechanical abnormalities.

Analysis of polyps reveals a grossly oedematous submucosa with a cellular infiltrate of predominantly plasma cells, lymphocytes, macrophages and eosinophils. Polyps also contain high levels of histamine, presumably from mast cell degranulation.

Polyps usually present in adulthood. In children, one must first exclude other causes such as cystic fibrosis or a meningocoele.

Among non-asthmatics, polyps are more common in men than in women, in a ratio of 2-4 to 1. Among asthmatics, the sex incidence is equal. Nasal polyps develop in 25% of patients with asthma, and 25% of patients initially presenting with nasal polyps, develop asthma as adults.

About 8% of patients with nasal polyps also have asthma and aspirin sensitivity - Samster's triad.