Eosinophil Peroxidase Staining Enhances the Diagnostic Utility of the Cytosponge in Eosinophilic Esophagitis

INTRODUCTION: We aimed to assess the diagnostic utility of eosinophil peroxidase (EPX) staining on Cytosponge (CS) samples in eosinophilic esophagitis (EoE). METHODS: Esophageal biopsy (BX) samples from adult subjects with EoE were assessed using peak eosinophils per high-power field (eos/hpf), EPX, and the EoE histologic scoring system. EPX staining and eos/hpf were compared (BX vs CS). RESULTS: CS EPX positivity correlated with eos/hpf (CS [r = 0.82, P < 0.0001]; BX [r = 0.65, P < 0.0001]) and EoE histologic scoring system (grade [r = 0.62, P < 0.00001]; stage [r = 0.61, P < 0.0001]). CS EPX identified subjects with active EoE (area under the curve = 0.86, P < 0.0001). DISCUSSION: The correlation of CS EPX with eosinophilic inflammation and histologic disease severity supports its diagnostic utility in EoE.