Nasal Polyps — the Unilateral Red Flag

Nasal polyps are usually bilateral, inflammatory, and benign — but a unilateral polyp is a red flag until proven otherwise. Their pathology, the associations worth knowing (Samter's triad, allergic fungal disease, cystic fibrosis), and the steroids-then-surgery management.

Most nasal polyps are benign, and the clinically important fact about them is the one that isn’t. They are inflammatory masses of oedematous sinonasal mucosa, classically grey and translucent, growing into the nose from the middle meatus and ethmoid region. When they are bilateral they are almost always part of chronic rhinosinusitis with nasal polyps (CRSwNP) and benign. When a polyp is unilateral, that pattern breaks, and it has to be treated as a possible tumour until proven otherwise.

What they are

Histologically, inflammatory nasal polyps contain mucus (goblet) cells and eosinophils within an oedematous stroma. That eosinophil-rich inflammatory picture is what distinguishes a true inflammatory polyp from neoplastic mimics — for example an inverting papilloma, which lacks those features and instead shows epithelium inverting down into the underlying stroma.

Bilateral vs unilateral

This distinction is what keeps a missed tumour off your conscience:

Bilateral polyps are usually inflammatory (CRSwNP): the common, benign picture.
A unilateral nasal mass is a red flag that demands a broader differential and, usually, biopsy for confirmation. Consider an antrochoanal polyp, an inverting papilloma, and malignancies including squamous cell carcinoma, esthesioneuroblastoma, and lymphoma.

Because a unilateral lesion can be vascular, biopsy is best done under controlled conditions in theatre if the mass is friable, vascular, or if significant bleeding is a concern — never a casual clinic snip of an unknown unilateral mass (consider a vascular tumour or an encephalocele first).

Key associations

Chronic rhinosinusitis with nasal polyps (CRSwNP) — polyps are the polyp phenotype of CRS.
Aspirin-exacerbated respiratory disease (Samter’s triad) — the triad of aspirin sensitivity + asthma + nasal polyposis.
Allergic fungal rhinosinusitis (AFRS) — bilateral polyps with thick, eosinophil-laden “allergic fungal mucin” containing non-invasive fungal hyphae.
Cystic fibrosis — cystic fibrosis is one of the systemic conditions guidelines specifically recommend assessing for in a patient with chronic rhinosinusitis and polyps (alongside asthma, immunodeficiency, and ciliary dyskinesia). Polyps in a child in particular should raise the possibility of cystic fibrosis, in whom nasal polyps are otherwise uncommon.

Clinical presentation

Nasal obstruction — chronic congestion and difficulty breathing through the nose; the commonest complaint.
Loss of smell (anosmia) — fluctuant or complete, from inflammatory obstruction of the olfactory cleft; often prominent in CRSwNP.
Rhinorrhoea and postnasal drip — thick discharge, occasional dark crusting.
Frontal headache, and epistaxis — the latter more concerning in unilateral or neoplastic disease.

Investigations

Nasal endoscopy — confirms polypoid masses, establishes bilateral vs unilateral, and assesses the middle meatus and ostiomeatal complex.
CT of the paranasal sinuses — the imaging of choice for the soft-tissue extent and any bony change; bone remodelling or an expansile appearance raises suspicion of inverting papilloma or AFRS rather than simple inflammatory polyps.
Biopsy — required to confirm any unilateral mass, performed in theatre if the lesion is friable or vascular.

Management

The pattern mirrors CRS: anti-inflammatory medical therapy first, surgery for the refractory — and treatment is ongoing, because polyps recur.

Topical intranasal corticosteroids — the mainstay for controlling symptoms and delaying re-formation of polyps.
Short courses of oral corticosteroids — e.g. a ~2-week course of prednisone to shrink polyps for symptom relief or before surgery.
Functional endoscopic sinus surgery (FESS) — the surgical mainstay: remove polyps and secretions and open the sinus outflow tracts, which also makes post-operative topical rinses and sprays far more effective. A microdebrider is used to remove polypoid tissue precisely.
Recurrence is the rule, not the exception — symptoms often return within weeks if therapy stops, and recurrence is more frequent in patients who are not compliant with post-operative topical or systemic steroids. Polyp disease is controlled, not cured — which is why maintenance topical steroids matter.

Frequently Asked Questions

Are nasal polyps dangerous? Bilateral inflammatory polyps are benign, though they cause troublesome obstruction and smell loss. The danger is a unilateral polyp or mass, which can be a tumour (inverting papilloma, squamous cell carcinoma, esthesioneuroblastoma, lymphoma) or an antrochoanal polyp, and must be investigated and biopsied rather than assumed benign.

Why does a one-sided nasal polyp need investigating when a two-sided one usually doesn’t? Because inflammatory polyps are typically bilateral. A unilateral lesion breaks that pattern and widens the differential to include neoplasia. Endoscopy defines the side, CT shows any bony destruction or expansion, and biopsy (often in theatre, as the lesion may be vascular) confirms the diagnosis before treatment.

What conditions are nasal polyps associated with? Chronic rhinosinusitis with nasal polyps (CRSwNP), aspirin-exacerbated respiratory disease (Samter’s triad: aspirin sensitivity, asthma, and polyps), allergic fungal rhinosinusitis, and — importantly in children — cystic fibrosis. Guidelines recommend assessing polyp/CRS patients for asthma, cystic fibrosis, immunodeficiency, and ciliary dyskinesia.

Do nasal polyps come back after surgery? Frequently. Surgery (FESS) clears the polyps and opens the sinuses, but polyp disease is an ongoing inflammatory condition — symptoms often recur within weeks if treatment stops, and recurrence is commoner in patients who don’t keep up their post-operative steroid sprays. Long-term topical corticosteroids are central to keeping them at bay.

Should a child with nasal polyps be tested for cystic fibrosis? Nasal polyps are uncommon in children, so their presence should prompt consideration of cystic fibrosis, which guidelines list among the systemic conditions to assess in polyp/CRS patients. The threshold to investigate for it is low in the paediatric age group.