CORRESPONDENCE

The aetiology of simple nasal polyps has been argued about for years. An allergic origin has been proposed, one ofthe arguments for this being the occurrence of nasal polyps in atopic subjects with allergic vasomotor rhinitis and extrinsic asthma. Pepys & Duveen (1951), however, pointed out the high incidence of negative skin testing in patients with nasal polyps. Caplin, Haynes & Houser (1968) also pointed out the similarity of the pale boggy nasal mucosa with nasal polyps of all kinds, and attributed this to mechanical causes rather than to allergy. Furthermore the association of polyps with cystic fibrosis (Rulon, Brown & Logan, 1963) and with aspirin hypersensitivity asthma (Caplin, Haynes & Spahn, 1971), would be surprising if allergy were a primary cause. Berdal (1954) has shown elevated reagin levels in nasal polyp fluid, and Donovan et al. (1970) have shown high local IgE concentrations in nasal polyp fluid not corresponding with serum IgE levels, arguing for the presence of local allergy. In asthmatic subjects, if allergic rhinitis predisposed to nasal polyp formation, the age distribution should be in the younger group. This is not the case. Brown (1969) in his series showed the main age distribution to be 30-70 years. Clinical impression also suggests that while rhinitis is common in all asthmatics, nasal polyps are not more frequent in the extrinsic group. A retrospective study by me of asthmatic patients attending an outpatient clinic for the last 7 years showed the following interesting figures: