Nasal polyps

Nasal polyps are benign swellings of the ethmoid sinus mucosa. Histologically polyps consist of a water-logged stroma infiltrated with eosinophils. The cause of polyp. for­mation is unknown but it is thought that it may be related to a disorder of arachidonic acid metabolism. Nasal polyps are erroneously linked to allergic rhinitis, but many patients with allergic rhinitis never have polyps and many patients who suffer from nasal polyposis have no evidence of nasal allergy. Approximately a third of patients with nasal polyps also have asthma, while the triad of nasal polyps, aspirin allergy and asthma is not uncommon.

The vast majority of nasal polyps arises from the ethmoid sinuses, each individual ethmoid air cell giving rise to a single polyp as its swollen mucosal lining prolapses out of the air cell to hang down inside the nasal cavity. Polyps can arise from the other nasal sinuses, and a single large polyp arising from the maxillary antrum is referred to as an antrochoanal polyp. This usually fills the nose and eventually prolapses down into the nasopharynx. The diagnosis can often be made by looking into the patient’s mouth and observing the fundus of the polyp hanging down beyond the free margin of the soft palate. Ethmoid polyps are usually bilateral but when unilateral in an adult or associated with bleeding then malignancy must be excluded. Nasal polyps are unusual in children and if multiple often occur in conjunction with cystic fibrosis in 10 per cent of cases. A unilateral nasal polyp in a child must be distinguished from a meningocele or encephalocele by high-resolution CT scanning of the anterior cranial fossa.

Clinical features

Polyps cause nasal obstruction associated with watery rhinor­rhoea and often anosmia. They are easily identifiable within the nose as pale, semitransparent grey masses which are mobile and insensitive when palpated with a fine probe, allowing them to be distinguished from turbinate hypertrophy. Extensive nasal polyposis often gives rise to secondary pan sinusitis, by occluding the ostia and interfering with sinus ventilation. If left untreated they will eventually result in expansion of the nose and prolapse through the nasal vestibule (Fig. 39.10).

Management of nasal polyps

Polyps are best treated by surgical removal either by avulsion with a nasal snare or with a powered nasal microresector (Fig. 39.11). Antral lavage should be performed at the same time. Benign transitional cell papilloma (inverted papilloma) can be mistaken for simple nasal polyps (see later) and therefore the polyps should always be submitted for histological examination.

Polyps often recur in a seemingly random and unpre­dictable way. There is evidence to suggest that long-term treatment with low-dose topical nasal steroids (beta­methasone) postoperatively lessens the tendency for polyps to recur. After multiple recurrence external ethmoidectomy should be considered. Although polyp formation may still occur after the procedure, the interval between recurrences will be longer. Polyps usually shrink while a patient is taking oral steroids but recur when treatment is stopped.

Nasal polyps summary

Polyps are insensitive to touch

      Transitional papilloma may be mistaken for simple polyps

Polyps can be removed by nasal snare or powered nasal microresector

Recurrent polyps, may require external ethmoidectomy

      Meningocele and encephalocele should be excluded in children with polyps

Bleeding polyps may indicate malignancy