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