Nasal Polyps — Antrochoanal vs Ethmoidal Polyps, Samter's Triad, CRSwNP and FESS

Nasal polyps are benign, inflammatory and hyperplastic outgrowths of the sinonasal mucosa. Most occur in patients with chronic rhinosinusitis (CRS), which is why the condition is usually called chronic rhinosinusitis with nasal polyps (CRSwNP). Polyps are also associated with aspirin-exacerbated respiratory disease (AERD), systemic vasculitis such as eosinophilic granulomatosis with polyangiitis (EGPA) and cystic fibrosis.

On endoscopy they look like smooth, grey, semi-translucent, mobile masses arising from the middle meatus or sphenoethmoidal recess. Patients complain of the cardinal CRS symptoms — nasal obstruction, facial congestion, rhinorrhoea and reduced or lost smell — and sometimes reduced taste.

• Localised polyps — usually reactive; the antrochoanal polyp is the classic example.
• Diffuse polyposis — seen in CRSwNP; in the West most is driven by T-helper 2 (Th2) eosinophilic, IgE-mediated inflammation.
• Systemic polyposis — nasal manifestation of a systemic disease such as cystic fibrosis or EGPA.

The comparison below is the single most tested part of this topic. Think of the antrochoanal polyp as a solitary, one-sided lesion of the young that grows backwards, and of ethmoidal polyposis as a multiple, two-sided disease of adults that is part of chronic inflammatory airway disease.

AERD, also called Samter's triad, is a chronic condition made up of asthma, recurrent nasal polyps and hypersensitivity to aspirin and other NSAIDs. Every patient with nasal polyps should be asked about asthma and about reactions to aspirin or NSAIDs.

Mechanism: aspirin and NSAIDs inhibit cyclo-oxygenase (COX). Arachidonic acid is then shunted down the lipoxygenase pathway, increasing production of cysteinyl leukotrienes — which cause bronchospasm, nasal congestion and mucosal inflammation in susceptible people.

Chronic rhinosinusitis means sinonasal symptoms with mucosal inflammation lasting 12 weeks or more, supported by objective evidence (endoscopy or CT). CRS affects about 10.9% of Europeans, and 25–30% of CRS patients have nasal polyps. CRSwNP usually presents between 40 and 60 years, more often in men. Allergic (eosinophilic) polyps are the most common histological type — about 86% in one series.

The diagnosis of CRSwNP is clinical: polyps seen on anterior rhinoscopy or endoscopy plus at least two cardinal symptoms. Histology classically shows oedematous stroma, tissue eosinophils, plasma cells, goblet-cell hyperplasia and a thickened basement membrane.

• Children with polyps: think cystic fibrosis — CF polyps are neutrophil-driven and severe without an obvious allergic trigger, especially in preteens, teens and young adults.
• Polyps with asthma and eosinophilia plus vasculitis features: think EGPA (formerly Churg-Strauss).
• Polyps with asthma and NSAID reactions: think AERD.

1. Intranasal corticosteroids (budesonide, fluticasone, mometasone) used twice daily, plus high-volume, low-pressure saline irrigation for about 2–3 months. Adherence is the main reason for failure and recurrence.
2. Short pulses of oral corticosteroids for severe disease, with care in diabetes and hypertension.
3. Antibiotics only for acute bacterial exacerbations; macrolides or doxycycline have a role in selected (neutrophilic, low-IgE) cases.
4. Aspirin desensitisation in AERD.
5. Biologics (monoclonal antibodies) for refractory disease — e.g. dupilumab, an anti–IL-4Rα antibody blocking IL-4 and IL-13 signalling, approved by the US FDA for CRSwNP in June 2019.

Antrochoanal polyps are the exception: they do not respond usefully to medical treatment. Treatment is surgical from the start.

Functional endoscopic sinus surgery (FESS) grew out of Messerklinger's work on mucociliary clearance. Its goals are to enlarge the natural sinus ostia, restore aeration, improve mucociliary transport and open a route for topical drugs — not to strip all mucosa. It is planned when CRSwNP is refractory to adequate medical treatment.

• Key anatomy: the middle meatus drains the frontal, maxillary and anterior ethmoid sinuses; the uncinate process is the first lamella met there, so uncinectomy is an early step. The lamina papyracea (orbit) lies lateral to the ethmoids.
• Posterior ethmoid cells drain to the sphenoethmoidal recess (superior meatus).
• Steroid-eluting stents may be placed to keep sinuses open and release steroid for 30 days or more.
• Post-operative intranasal steroids and saline are essential — surgery removes obstruction but not the underlying inflammation.
• Risks: significant bleeding, epiphora (nasolacrimal injury) and, rarely, orbital or intracranial injury. Image guidance is used for revision or distorted anatomy.