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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Allergy</journal-id>
<journal-title>Frontiers in Allergy</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Allergy</abbrev-journal-title>
<issn pub-type="epub">2673-6101</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/falgy.2025.1628864</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Allergy</subject>
<subj-group>
<subject>General Commentary</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Commentary: Tissue eosinophil level as a predictor of control, severity, and recurrence of Chronic Rhinosinusitis with Nasal Polyps</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes"><name><surname>Gelardi</surname><given-names>Matteo</given-names></name>
<xref ref-type="corresp" rid="cor1">&#x002A;</xref><uri xlink:href="https://loop.frontiersin.org/people/1239486/overview"/><role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/><role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/></contrib>
</contrib-group>
<aff><institution>Department of Otolaryngology, University of Foggia</institution>, <addr-line>Foggia</addr-line>, <country>Italy</country></aff>
<author-notes>
<fn fn-type="edited-by"><p><bold>Edited by:</bold> Hideyuki Kawauchi, Shimane University, Japan</p></fn>
<fn fn-type="edited-by"><p><bold>Reviewed by:</bold> Ramiza Ramli, Universiti Sains Malaysia Health Campus, Malaysia</p></fn>
<corresp id="cor1"><label>&#x002A;</label><bold>Correspondence:</bold> Matteo Gelardi <email>matteo.gelardi@unifg.it</email></corresp>
</author-notes>
<pub-date pub-type="epub"><day>26</day><month>06</month><year>2025</year></pub-date>
<pub-date pub-type="collection"><year>2025</year></pub-date>
<volume>6</volume><elocation-id>1628864</elocation-id>
<history>
<date date-type="received"><day>14</day><month>05</month><year>2025</year></date>
<date date-type="accepted"><day>13</day><month>06</month><year>2025</year></date>
</history>
<permissions>
<copyright-statement>&#x00A9; 2025 Gelardi.</copyright-statement>
<copyright-year>2025</copyright-year><copyright-holder>Gelardi</copyright-holder><license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the <ext-link ext-link-type="uri" xlink:href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution License (CC BY)</ext-link>. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p></license>
</permissions>
<kwd-group>
<kwd>CRSwNP recurrent</kwd>
<kwd>mast-cell</kwd>
<kwd>nasal cytology</kwd>
<kwd>Clinical-Citological Grading</kwd>
<kwd>eosinophils</kwd>
<kwd>microscopy</kwd>
</kwd-group><counts>
<fig-count count="0"/>
<table-count count="0"/><equation-count count="0"/><ref-count count="8"/><page-count count="3"/><word-count count="0"/></counts><custom-meta-wrap><custom-meta><meta-name>section-at-acceptance</meta-name><meta-value>Rhinology</meta-value></custom-meta></custom-meta-wrap>
</article-meta>
</front>
<body>
<related-article id="RA1" related-article-type="commentary-article" journal-id="Front. Allergy" journal-id-type="nlm-ta" xlink:href="10.3389/falgy.2025.1549332" ext-link-type="doi">A Commentary on <article-title>Tissue eosinophil level as a predictor of control, severity, and recurrence of Chronic Rhinosinusitis with Nasal Polyps</article-title> By Vizcarra-Melgar J, S&#x00E1;nchez-G&#x00F3;mez S, L&#x00F3;pez-Gonz&#x00E1;lez N, Moreno-Luna R, Gonz&#x00E1;lez-Garc&#x00ED;a J and Maza-Solano J (2025). Front. Allergy 6:1549332. doi: <object-id>10.3389/falgy.2025.1549332</object-id></related-article>
<p>Dear Editor,</p>
<p>I read with great interest the paper by Vizcarra-Melgar and colleagues, which revisits the belief that tissue eosinophil counts alone can stratify chronic rhinosinusitis with nasal polyps (CRSwNP). Their large series and use of POLINA composite criteria are commendable. Yet several methodological and conceptual issues, detailed below, suggest that the negative results may derive more from study design than from genuine irrelevance of tissue data (<xref ref-type="bibr" rid="B1">1</xref>).</p>
<sec id="s1"><label>1</label><title>A pronounced ceiling effect</title>
<p>In the cohort, 81.5&#x0025; of specimens exceeded the &#x2265;10 eosinophils&#x00B7;HPF-<sup>1</sup> threshold and more than half surpassed 55 eosinophils&#x00B7;HPF-<sup>1</sup> (<xref ref-type="bibr" rid="B1">1</xref>). When a predictor clusters near its upper bound, statistical power to discriminate outcomes collapses. Re-analysing the dataset with higher cut-offs or, preferably, modelling eosinophils as a continuous variable (e.g., restricted cubic splines) could unmask hidden dose&#x2013;response trends.</p>
</sec>
<sec id="s2"><label>2</label><title>The added value of the Clinical-Cytological Grading (CCG)</title>
<p>Nasal cytology&#x2014;simple, rapid, inexpensive&#x2014;captures inflammatory endotypes that routine histology misses (<xref ref-type="bibr" rid="B2">2</xref>). The Clinical-Cytological Grading (CCG) combines the dominant cellular pattern (eosinophils, mast cells, neutrophils, or mixed) with &#x201C;type-2 amplifiers&#x201D; such as asthma, aspirin-exacerbated respiratory disease and inhalant allergy. A score &#x2265;7 correlates with poor disease control and higher Lund&#x2013;Mackay scores (<xref ref-type="bibr" rid="B3">3</xref>, <xref ref-type="bibr" rid="B4">4</xref>), and underpins the Prognostic Index of Recurrence (PIR) prospectively linked to post-surgical relapse (<xref ref-type="bibr" rid="B3">3</xref>). By integrating local and systemic information, CCG avoids the tunnel vision of single-biomarker approaches. Stratifying the present dataset by CCG might show that histological eosinophilia seems irrelevant only because the inflammatory milieu was incompletely captured.</p>
</sec>
<sec id="s3"><label>3</label><title>The missing mast-cell piece</title>
<p>Histopathology was labelled eosinophilic, neutrophilic or mixed, but mast cells were not quantified. This omission matters. Intra-epithelial mast cells co-localise with eosinophils in recalcitrant CRSwNP and parallel severe anosmia (<xref ref-type="bibr" rid="B4">4</xref>); their presence independently predicts early relapse after functional endoscopic sinus surgery (<xref ref-type="bibr" rid="B5">5</xref>). IgE-bearing mast cells are plausible drivers of &#x201C;type 2-high&#x201D; remodelling and of the favourable response to omalizumab. Neglecting them likely underestimates local inflammatory load and helps explain the weak linkage between tissue data and clinical endpoints.</p>
</sec>
<sec id="s4"><label>4</label><title>Harmonising outcome definitions</title>
<p>The authors sensibly adopted POLINA to grade severity and control. Earlier histopathological series, however, relied on SNOT-22, VAS or Lund&#x2013;Mackay alone. Because these indices capture overlapping yet distinct domains, comparing effect sizes across studies is problematic. A consensus framework that cross-walks CCG, POLINA, EPOS control criteria and biological &#x201C;passport&#x201D; variables (blood eosinophils, total IgE, periostin) would enhance reproducibility and enable meta-analytic synthesis.</p>
</sec>
<sec id="s5"><label>5</label><title>Practical implications</title>
<p>Clinicians favour tools that are quick, cheap and predictive. A May-Gr&#x00FC;nwald-Giemsa smear takes under ten minutes, costs pennies and has a gentle learning curve (<xref ref-type="bibr" rid="B2">2</xref>). One slide reveals the endotype, flags a high CCG (&#x2265;7) with elevated relapse risk, and guides decisions on biologics or peri-operative oral steroids (<xref ref-type="bibr" rid="B6">6</xref>). Until validated molecular panels become affordable, CCG offers a pragmatic bridge between histology and bench-top omics.</p>
</sec>
<sec id="s6"><label>6</label><title>Suggestions for future research</title>
<list list-type="simple">
<list-item><label>&#x2022;</label>
<p>Apply continuous or higher eosinophil thresholds to blunt the ceiling effect.</p></list-item>
<list-item><label>&#x2022;</label>
<p>Quantify mast cells systematically (May-Gr&#x00FC;nwald-Giemsa or tryptase immunohistochemistry) to refine tissue phenotypes (<xref ref-type="bibr" rid="B7">7</xref>).</p></list-item>
<list-item><label>&#x2022;</label>
<p>Compare CCG, POLINA severity and blood biomarkers head-to-head in prospective multicentre designs.</p></list-item>
<list-item><label>&#x2022;</label>
<p>Validate the PIR in non-Mediterranean cohorts to test geographic generalisability.</p></list-item>
<list-item><label>&#x2022;</label>
<p>Integrate multi-omics (transcriptome, proteome) with cytology to uncover targets beyond the IL-4/IL-5/IgE axis (<xref ref-type="bibr" rid="B8">8</xref>).</p></list-item>
</list>
</sec>
<sec id="s7" sec-type="conclusions"><label>7</label><title>Conclusion</title>
<p>Vizcarra-Melgar et al. convincingly show that low-threshold tissue eosinophilia alone cannot explain the full clinical spectrum of CRSwNP (<xref ref-type="bibr" rid="B1">1</xref>). Their data illustrate the limits of single-cell-type metrics rather than the futility of tissue analysis. Incorporating the Clinical-Cytological Grading and explicitly counting mast cells can overcome the ceiling effect, capture mixed inflammatory phenotypes and yield a pragmatic bedside prognostic index&#x2014;aligning with precision-medicine ambitions and benefiting patients with this stubbornly relapsing disease.</p>
</sec>
</body>
<back>
<sec id="s8" sec-type="author-contributions"><title>Author contributions</title>
<p>MG: Writing &#x2013; review &#x0026; editing, Writing &#x2013; original draft.</p>
</sec>
<sec id="s9" sec-type="funding-information"><title>Funding</title>
<p>The author declares that no financial support was received for the research and/or publication of this article.</p>
</sec>
<sec id="s10" sec-type="COI-statement"><title>Conflict of interest</title>
<p>The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec id="s12" sec-type="disclaimer"><title>Publisher&#x0027;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
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