Nasal Cytology in Allergic Rhinitis and Chronic Rhinosinusitis

Nasal cytology is the microscopic examination of cells obtained from the nasal mucosa, offering a direct window into local inflammatory processes. In allergic rhinitis, this technique distinguishes between different inflammatory phenotypes by quantifying eosinophils, mast cells and neutrophils on stained smears, thereby guiding targeted therapies such as antihistamines or immunotherapy. In chronic rhinosinusitis (CRS), and particularly in forms with nasal polyps (CRSwNP), cytology complements endoscopy and imaging by revealing mixed cell infiltrates that correlate with disease severity and recurrence risk. The dynamic interplay between epithelial damage, cytokine release and cellular recruitment underpins both symptom burden and response to surgical or biological treatments. Across a growing body of work, nasal cytology has emerged as an accessible, non‐invasive tool for endotyping upper airway inflammation, refining diagnostic classification and informing personalised management in precision rhinology.

Research from Nature Portfolio

Recent studies have refined the cytological-histological interface in CRS. One investigation into CRSwNP evaluated nasal polyps by both cytology and immunohistochemistry, revealing that intraepithelial mast cell counts correlate strongly with severity scores and recurrence risk. A threshold of six intraepithelial mast cells per high-power field was proposed to identify high-risk cases requiring tailored anti-inflammatory strategies. Another analysis of over 800 patients undergoing nasal scraping demonstrated that the epithelial-to-inflammatory cell ratio varies across rhinitis subtypes. In allergic rhinitis provoked by pollen, a paradoxical reduction in eosinophils despite intense inflammation highlighted that cellular patterns must be interpreted in context. The study established eosinophil percentages (>1% of inflammatory cells and 20% of total cells) as practical cut-offs to distinguish allergic from non-allergic presentations, supporting more precise clinical grading.

Nasal Cytology in Allergic Rhinitis and Chronic Rhinosinusitis publication trend

The graph below shows the total number of articles in nasal cytology in allergic rhinitis and chronic rhinosinusitis across all publications each year (not limited to Nature Index journals).

Technical terms

Nasal cytology: Microscopic analysis of cells collected from the nasal mucosa to characterise local inflammation and epithelial integrity.

Eosinophil: A granulocytic white blood cell implicated in type 2 immune responses and allergic inflammation, identifiable by its bilobed nucleus and cytoplasmic granules.

Mast cell: Tissue-resident innate immune cell that releases histamine and proteases during allergic reactions and contributes to epithelial remodelling.

Type 2 inflammation: An immune response driven by Th2 cytokines (for example, interleukin-4, interleukin-5 and interleukin-13), characterised by eosinophilic infiltration and IgE production.

Lamina propria: The connective tissue layer beneath the respiratory epithelium, containing immune cells, blood vessels and nerves.

References

1. Cytological Study of Topical Effect of Azelastine Hydrochloride on the Nasal Mucous Membrane Cells in Various Nasal Rhinitis Types. Cells (2023).
2. Eosinophil-mast cell pattern of intraepithelial infiltration as a marker of severity in CRSwNP. Scientific Reports (2023).
3. Nasal Cytology: A Easy Diagnostic Tool in Precision Medicine for Inflammation in Epithelial Barrier Damage in the Nose. A Perspective Mini Review. Frontiers in Allergy (2022).
4. Scraping nasal cytology in the diagnostics of rhinitis and the comorbidities. Scientific Reports (2022).
5. Sinonasal Biomarkers Defining Type 2-High and Type 2-Low Inflammation in Chronic Rhinosinusitis with Nasal Polyps. Journal of Personalized Medicine (2022).