BLOOD EOSINOPHIL COUNT (BEC) showed consistent diagnostic value for type 2 chronic rhinosinusitis (T2 CRS), regardless of allergic sensitisation, according to a new study. The findings also suggested that a BEC threshold of approximately 220–230/µL may be more appropriate for identifying tissue eosinophilia than the conventional threshold of 150/µL.
Researchers evaluated the diagnostic performance of BEC and serum total immunoglobulin E (IgE) in 177 patients with chronic rhinosinusitis (CRS) who underwent endoscopic sinus surgery.
T2 CRS was defined according to a tissue eosinophil count of at least 10 eosinophils per high-power field. The researchers assessed associations between BEC, blood eosinophil percentage, serum total IgE and tissue eosinophil count.
Patients were also categorised according to allergic sensitisation, allowing the researchers to assess whether the diagnostic performance of these blood-based markers differed between allergic and non-allergic groups.
Both BEC and blood eosinophil percentage were positively associated with tissue eosinophil count, irrespective of allergic sensitisation. Serum total IgE, however, did not demonstrate the same relationship.
Receiver operating characteristic analysis showed that the area under the curve for BEC remained comparable across the overall cohort and both allergic and non-allergic groups. This performance was also maintained when different histological definitions of T2 CRS were applied.
By comparison, serum total IgE demonstrated significantly lower area under the curve values than BEC. Its diagnostic performance was generally poorer among patients without allergic sensitisation.
The optimal BEC thresholds identified using the Youden index clustered around 220–230/µL, above the conventional threshold of 150/µL.
The findings support blood eosinophil count as a potentially useful surrogate marker for tissue eosinophilia in T2 CRS, including among patients without allergic sensitisation.
The researchers suggested that the findings could support a modest upward revision of the BEC threshold used when identifying T2 CRS. In contrast, serum total IgE appeared to have limited diagnostic utility for tissue eosinophilia-defined T2 CRS, particularly in non-allergic patients.
Further consideration of BEC alongside patient characteristics and tissue findings may therefore help inform the assessment and classification of T2 CRS.
Reference
Cho A et al. Predictive value of blood eosinophil count and serum total immunoglobulin E for type 2 chronic rhinosinusitis according to allergic sensitization status. Eur Arch Otorhinolaryngol. 2026;DOI: 10.1007/s00405-026-10527-y.
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