Nasal polyposis, eosinophil dominated inflammation, and allergy

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Abstract
A polyp is an oedematous mucous membrane which forms a pedunculating process with a slim or broad stalk or base. Nasal polyps originate in the upper part of the nose around the openings to the ethmoidal sinuses. The polyps extend into the nasal cavity from the middle meatus, resulting in nasal blockage and restricted airflow to the olfactory region. The polyp stroma is highly oedematous with a varying density of inflammatory cells. Nasal polyposis, consisting of recurrent, multiple polyps, is part of an inflammatory reaction involving the mucous membrane of the nose, paranasal sinuses, and often the lower airways. The polyps are easily accessible for immunological and histological studies and an increasing number of publications have appeared in recent years, including two monographs.1 2 Nasal polyps have long been associated with rhinitis and asthma. However, the role of allergy in the aetiology and pathogenesis of nasal polyps is a controversial issue. It has been postulated that allergy is an aetiological factor for nasal polyposis. If this is so, then it can be expected that allergic patients will have polyps more often than a control population and that patients with polyps have an increased occurrence of positive allergy testing. In this paper we will describe the possible connection between nasal polyposis and allergy, based on an analysis of (1) the occurrence of polyps and of allergy, (2) the anatomy and histology of nasal polyps, (3) the inflammation in nasal polyps, (4) the occurrence of positive allergy tests in patients with polyps, (5) the effect of allergen exposure on nasal symptoms in patients with polyps, and (6) the response to treatment. While the aetiology of nasal polyposis is unknown in many patients, in a few cases it is well defined. Polyps occur in most patients with allergic fungal sinusitis. In this …