Nasal Polyps: Diagnosis and Management

Introduction

Nasal polyps are benign, grape-like swellings of the nasal and sinus mucosa, most often occurring as part of chronic rhinosinusitis with nasal polyps (CRSwNP). They are almost always bilateral, and their presence changes the classification and treatment intensity of the underlying chronic rhinosinusitis, covered in more depth separately.¹

The key clinical skill is recognising the typical bilateral picture, appreciating its strong link to asthma and aspirin sensitivity, and knowing that a unilateral polyp is a fundamentally different problem that must not be managed the same way.

Aetiology and pathophysiology

Nasal polyps arise from chronic Type 2 (eosinophilic) inflammation of the sinonasal mucosa, driven by cytokines including IL-4, IL-5 and IL-13. Persistent inflammation causes oedema of the lamina propria, which prolapses as pedunculated, oedematous polyps, typically originating from the ethmoid sinuses and middle meatus.^1,2

This same Type 2 inflammatory process underlies asthma and allergic disease more broadly, which explains the well-recognised overlap between nasal polyps, asthma, and aspirin/NSAID sensitivity - the combination is known as Samter's triad (aspirin-exacerbated respiratory disease). Patients with this triad tend to have more severe, recurrent polyp disease that is harder to control.

Associations and risk factors

• Asthma, particularly late-onset or difficult-to-control asthma
• Aspirin or NSAID sensitivity (Samter's triad)
• Allergic rhinitis
• Chronic rhinosinusitis
• Cystic fibrosis - an important cause in children, in whom polyps are otherwise unusual
• Primary ciliary dyskinesia
• Allergic fungal rhinosinusitis

Clinical features

The dominant symptoms are progressive nasal obstruction and hyposmia or anosmia (reduced or lost sense of smell), which is often the symptom patients find most troublesome and can be the presenting complaint even before obstruction is prominent.¹ Watery or mucoid rhinorrhoea, postnasal drip, snoring and mouth breathing are also common, and large or long-standing polyps can cause a sensation of facial pressure.

Unlike acute or infective sinus disease, nasal polyps are typically painless. Significant facial pain, bleeding, or unilateral symptoms are atypical for straightforward polyp disease and should prompt reconsideration of the diagnosis rather than being attributed to "bad polyps".

Examination

On anterior rhinoscopy, polyps appear as pale, grey, glistening, mobile swellings, in contrast to the pink, vascular, tender inferior turbinates they can be confused with. A useful bedside discriminator is gentle palpation with a probe: polyps are typically insensitive to touch, whereas turbinates are sensitive and cause the patient discomfort.¹

Nasal endoscopy, performed in secondary care, allows full visualisation and staging of polyp extent and is the standard way of assessing severity and response to treatment. A unilateral polypoid mass, particularly one that is friable, bleeds easily, or is associated with facial numbness or bony erosion on imaging, should be regarded with suspicion until proven otherwise.

Differential diagnosis

• Inferior turbinate hypertrophy: pink, tender, and reduces with decongestant, unlike a true polyp
• Antrochoanal polyp: a solitary, unilateral polyp arising from the maxillary sinus and extending back into the nasopharynx, most common in children and young adults - benign, but needs complete surgical excision including its antral origin to prevent recurrence
• Inverted papilloma: a unilateral, locally aggressive benign tumour with malignant potential, needing biopsy and complete excision
• Sinonasal malignancy: unilateral mass, particularly with bleeding, pain or facial numbness
• Encephalocele: a rare cause of a unilateral nasal mass in a child, representing herniated brain tissue - biopsy is contraindicated until imaging has excluded this, given the risk of CSF leak and meningitis

Investigations

Nasal endoscopy confirms the diagnosis and grades polyp size and extent. CT of the paranasal sinuses is used before surgery to map the anatomy and extent of disease, and to assess the ostiomeatal complex.¹

Any unilateral polypoid mass in an adult should be biopsied to exclude malignancy or inverted papilloma, and imaging (CT, with MRI if the lesion could represent an encephalocele or if bony erosion is seen) should generally precede biopsy in atypical or suspicious cases. In children with nasal polyps, a sweat test or genetic testing for cystic fibrosis should be considered, since polyps are otherwise unusual at a young age.

Management

Intranasal corticosteroids are first-line treatment for bilateral nasal polyps and reduce inflammation, polyp size, and associated symptoms; they are used long term given the chronic, relapsing nature of the disease. Saline nasal irrigation is a useful adjunct that helps clear mucus and improves the effectiveness of topical steroid.¹

A short course of oral corticosteroids is used for more severe disease, to rapidly shrink large polyps, or as preparation before surgery. Patients who fail an adequate trial of medical therapy, or who have significant persistent obstruction or anosmia, are referred for endoscopic sinus surgery (polypectomy/FESS) to remove polyps and improve sinus drainage.

For severe, recurrent nasal polyposis, particularly with coexisting asthma, biologic therapies targeting the Type 2 inflammatory pathway (e.g. anti-IL-4/IL-13 or anti-IgE agents) are increasingly used as an alternative or adjunct to repeated surgery. In patients with confirmed aspirin-exacerbated respiratory disease, aspirin desensitisation under specialist supervision can reduce polyp recurrence and improve asthma control.

Solitary lesions such as an antrochoanal polyp are managed surgically with complete excision of the polyp and its site of origin in the maxillary sinus, since simple polypectomy alone has a high recurrence rate if the antral component is left behind.

Complications

• Persistent or permanent anosmia, even after successful treatment of obstruction
• Recurrence after surgery, particularly with coexisting asthma and aspirin sensitivity
• Sleep disturbance and obstructive symptoms affecting quality of life
• Chronic rhinosinusitis complications (orbital or intracranial spread) in severe, poorly controlled disease, though rare
• Delayed diagnosis of malignancy if a unilateral lesion is mistakenly treated as routine bilateral polyp disease

Red flags

Prognosis

Nasal polyps are a chronic, relapsing condition rather than a one-off problem to be cured. Many patients achieve good long-term symptom control with regular intranasal corticosteroids and saline irrigation, but recurrence after surgery is common, particularly in those with asthma and aspirin sensitivity, who often need ongoing medical therapy or repeat surgery over time.¹ Loss of smell is the symptom most likely to persist despite otherwise successful treatment.