...we determined whether EoP levels correlated with EoEHSS histologic metrics. Given that the EoEHSS evaluates both eosinophil inflammation (EI, ie, eosinophil abscesses, eosinophil surface layering, and surface epithelial alteration) and pathologic features independent of tissue eosinophilia (ie, basal zone hyperplasia BZH, dilated intercellular spaces, dyskeratotic epithelial cells, and lamina propria fibrosis), we investigated the relationship between blood EoP levels and each pathologic feature assessed by the EoEHSS (Fig 1, E). ...future studies with larger patient cohorts and longitudinal assessments of EoP levels within individuals are needed before this potential biomarker is ready for clinical application.Appendix Abbreviation Pathologic feature Description EI Eosinophil inflammation Intraepithelial eosinophils quantified in the most densely inflamed hpf EA Eosinophil abscesses Solid mass of intraepithelial eosinophils SL Eosinophil surface layering Linear alignment of at least 3 intraepithelial eosinophils positioned parallel to the epithelial surface BZH Epithelial basal zone hyperplasia Basal zone comprising >15% of the total epithelial thickness DIS Dilated intercellular spaces Circumferential paracellular spaces around squamous epithelial cells that exhibit intercellular bridges SEA Surface epithelial alteration Altered tinctorial properties of the surface epithelial cells that manifest as darker red staining DEC Dyskeratotic epithelial cells Individual cells with deeply eosinophilic cytoplasm and small, round hyperchromatic nuclei LPF Lamina propria fibrosis Thickened connective tissue fibers in the lamina propria Table E1 Pathologic features of EoEHSS Characteristic Inactive EoE (PEC < 15/hpf) Active EoE (PEC ≥ 15/hpf) Significance (P) Number (n) 14 17 — Age (y),† median (interquartile range) 8.0 (3.3-13.1) 14.3 (6-16.9) .07 (NS) Sex: male, % 50 65 .48 (NS) Atopy,‡ % 79 82 >.99 (NS) PEC (eos/hpf), median (interquartile range) 0.5 (0-3) 52 (36-86) <.001 Absolute blood EoP count (EoP/mL blood), median (interquartile range) 13.5 (5.5-30.3) 37 (20.5-49.0) <.001 Table E2 Subjects' demographic characteristics∗