Charcot-Leyden crystals may predict nasal polyp recurrence after endoscopic sinus surgery
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The presence of Charcot-Leyden crystals in nasal tissues may be used to predict the recurrence of eosinophilic chronic rhinosinusitis with nasal polyps, according to a letter published in Clinical and Translational Allergy.
Wenyi Chen, of the department of otolaryngology-head and neck surgery at Third Affiliated Hospital of Sun Yat-Sen University in Guangzhou, China, and colleagues described these formations as needle-shaped bipyramidal galectin-10 crystals that can be detected by morphological methods and that have been considered “classic hallmarks of eosinophilic inflammation.”
Researchers of the retrospective study examined data from 110 patients who had endoscopic sinus surgery for CRSwNP between January and December 2016. During the 24-month follow-up, 30% (n = 33) experienced polyp recurrence.
Compared with the group that did not experience polyp recurrence, the group that did had a higher rate of comorbid asthma (27.27% vs. 7.79%; P = .015) and a higher percentage of male patients (84.5% vs. 57.14%; P = .005) .
The group with recurrent polyps also had higher counts of Charcot-Leyden crystals (P < .001) and eosinophils (P < .001) in their nasal tissues, with significant elevations in percentage (P = .001) and number (P < .001) of eosinophils in peripheral blood as well.
Using hematoxylin and eosin staining, the researchers found Charcot-Leyden crystal structures in 26.36% of the patients overall and in 64.44% of the patients with eosinophilic CRSwNP, but they did not observe them in the patients who had noneosinophilic CRSwNP or the control group.
Researchers also detected Charcot-Leyden crystal structures in diseased ethmoid mucosa but at a lower rate than what they observed in nasal polyps, indicating that eosinophils may dominate chronic rhinosinusitis as well as nasal polyps.
Overall, a larger proportion of the recurrence group had vs. did not have Charcot-Leyden crystals (84.85% vs. 15.15%) as well as eosinophilic vs. non eosinophilic CRSwNP (87.88% vs. 12.12%), suggesting that these crystals and eosinophils both are closely associated with recurrence, the researchers wrote.
Tissue Charcot-Leyden crystal counts appeared significantly associated with polyp recurrence on univariate (OR = 2.203; 95% CI, 1.256-3.865) and adjusted (OR = 2.078; 95% CI, 1.269-3.402) logistic regression analyses.
Additional potential predictors for postoperative polyp recurrence on univariate analysis included:
- tissue eosinophil count (OR = 1.077; 95% CI, 1.045-1.109);
- male sex (OR = 3.895; 95% CI, 1.33-11.403);
- comorbid asthma (OR = 3.974; 95% CI, 1.229-12.85);
- peripheral blood eosinophil count (OR = 3.804; 95% CI, 1.003-14.428); and
- peripheral blood eosinophil percentage (OR = 1.096; 95% CI, 1.011-1.187).
Using the maximal Youden index (YI), the researchers also determined that a Charcot-Leyden crystal count of 1 (YI = 0.835) was an optimal cutoff for predicting polyp recurrence with 84.8% sensitivity and 98.7% specificity.
Based on these findings, the researchers called Charcot-Leyden crystals in nasal polyps markers of eosinophilic inflammation, objective and promising predictors for recurrence of nasal polyps, and potential targets for CRSwNP treatment strategies.
Perspective
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These findings are not at all surprising. They reflect the intense eosinophilic inflammation present in CRSwNP.
However, there are limitations to the study that could affect its utility. It was retrospective, which can lead to selection bias. It also was a single center study. Given the difficulty in identifying the Charcot-Leyden crystals as noted by the authors, other centers may not have the same experience based on the pathologists who are reading the slides.
I am a little surprised that only 30% of the patients were recurrent, but the researchers excluded those patients who were not on nasal corticosteroids, so they may have picked a milder population.
These findings need to be confirmed in a multicenter study. Doctors would need to see the pathology report, and pathologists would need to be asked to identify Charcot-Leyden crystals. But if these crystals are present, combined with historical factors, they do help to predict recurrence.
The next step should be a multicenter study using real-world criteria. Most patients present on nasal steroids so, to be helpful, it is necessary to see if these findings would be applicable in a more real-world setting.
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