Nasal Polyposis

Nasal polyps are benign, oedematous outgrowths of inflamed sinonasal mucosa that protrude into the nasal cavity, typically arising bilaterally from the ethmoid sinuses and the middle meatus. Nasal polyposis is the clinical expression of chronic rhinosinusitis with nasal polyps, and it characteristically causes nasal obstruction and loss of smell.

Definition

Nasal polyps are benign, semi-translucent inflammatory swellings of the sinonasal mucosa; nasal polyposis denotes the presence of such polyps and is regarded as the phenotype of chronic rhinosinusitis with nasal polyps (CRSwNP).

Scope

The entry covers what nasal polyps are, how nasal polyposis relates to chronic rhinosinusitis with nasal polyps, the type 2 inflammatory mechanisms that drive it, its associated conditions, and the evidence framework including topical therapy and biologic agents. It is reference-educational and does not give individualised treatment advice.

Core questions

• What are nasal polyps and where do they arise?
• How does nasal polyposis relate to chronic rhinosinusitis and its endotypes?
• What is the role of type 2 inflammation and eosinophils in polyp formation?
• What conditions, such as aspirin-exacerbated respiratory disease, are associated with polyposis?

Key concepts

• Nasal polyps
• Chronic rhinosinusitis with nasal polyps (CRSwNP)
• Type 2 inflammation
• Eosinophilic inflammation
• Aspirin-exacerbated respiratory disease (AERD)
• Hyposmia and anosmia
• Recurrence after surgery
• Biologic therapy (anti-type-2)

Mechanisms

Nasal polyps form through sustained mucosal inflammation in which oedema, epithelial remodelling, and tissue eosinophilia produce the characteristic gelatinous outgrowths. In most polyposis the dominant pattern is type 2 inflammation, mediated by cytokines such as interleukin-4, -5, and -13 and marked by eosinophil recruitment; this endotype underlies the responsiveness of severe polyposis to biologic agents that block type 2 signalling, as shown for dupilumab. Polyps obstruct the nasal airway and the olfactory cleft, accounting for the prominent nasal blockage and smell loss. EPOS 2020 and ICAR-RS 2021 place polyposis within the endotype-based framework of chronic rhinosinusitis.

Clinical relevance

Nasal polyposis is a major cause of chronic nasal obstruction and smell loss and a frequent indication for sinus surgery, with a notable tendency to recur. Understanding its inflammatory basis clarifies why it is now treated within the type 2 inflammatory disease framework; this entry describes the condition and is not a basis for individual diagnosis or treatment.

Epidemiology

Nasal polyps are estimated to affect on the order of a few per cent of the general adult population, are more common in men and with increasing age, and are strongly associated with asthma and with aspirin-exacerbated respiratory disease. Polyposis tends to recur after medical or surgical treatment, contributing to its long-term burden.

Evidence & guidelines

EPOS 2020 and ICAR-RS 2021 frame the diagnosis and management of chronic rhinosinusitis with nasal polyps; Cochrane reviews summarise topical corticosteroid evidence, and phase 3 randomised trials of biologic agents, such as the LIBERTY NP SINUS dupilumab trials, established targeted anti-type-2 therapy for severe disease.

History

Nasal polyps have been described since antiquity and were long treated by mechanical removal, but understanding advanced markedly once endoscopic sinus surgery allowed thorough clearance of the ethmoid sinuses. The recognition of tissue eosinophilia and then of type 2 inflammation reframed polyposis as an immunologic disease, culminating in the introduction of biologic therapies targeting the type 2 pathway.

Debates

How should severe recurrent polyposis be managed between surgery and biologics?

With effective type 2-targeted biologics now available, there is active discussion about the relative roles and sequencing of endoscopic surgery and biologic therapy in severe or recurrent nasal polyposis, weighing efficacy, durability, and cost.

Key figures

• Wytske Fokkens
• Claus Bachert
• Valerie Lund
• Claire Hopkins
• Richard Orlandi

Seminal works

• fokkens-2020-epos
• bachert-2019-dupilumab
• orlandi-2021-icar

Frequently asked questions

Are nasal polyps cancerous?

No. Nasal polyps are benign inflammatory swellings of the sinonasal lining; however, a unilateral or atypical nasal mass warrants evaluation to exclude other diagnoses, which is a clinical judgement beyond the scope of this reference entry.

Why do nasal polyps cause loss of smell?

Polyps and the surrounding mucosal inflammation can obstruct the olfactory cleft high in the nose and involve the olfactory mucosa, which together impair the sense of smell.