Comparative study on different methods of detecting eosinophils in nasal polyps

Abstract

Objective: To investigate whether there were differences between the three stains for eosinophil counting in nasal polyps. Method: Three serial sections of formalin-fxed, paraffn-embedded tissues of 23 cases of nasal polyps were stained with Congo red,Chromotrope 2R and conventional HE staining, respectively. The stained sections were converted to digital pathology using a digital slice scanner. The qualitative assessment of the staining results was made in terms of specificity, contrast and background staining. Eosinophils were quantitatively evaluated and statistically analyzed using the Image J Analysis System and GraphPad Prism 5 statistical software. Result: Congo red staining and Chromotrope 2R staining were more specific than conventional HE staining. Chromotrope 2R had the lowest background staining. The majority of Congo red staining (n=20) was lighter in the background than in the conventional HE, while a small number of cases (n=3) background staining slightly stronger. Both Congo red staining and Chromotrope 2R staining had statistically significant differences compared with conventional HE staining (P<0.05), but there was no significant difference between Congo red staining and Chromotrope 2R staining (P>0.05). Conclusion: Congo red staining and Chromotrope 2R staining are more suitable for accurate counting of eosinophils, and the use of these two methods contributes to the harmonization of eosinophil count criteria in the ECRSwNP definition.