Food allergy and PPI-responsive esophageal eosinophilia

Background Eosinophilic esophagitis (EoE) is considered a chronic condition mediated by immune reaction to food and/or environmental allergens. Though first recognized decades ago, the characterization of EoE is ongoing and an important aspect of this process is the distinction between EoE and other forms of esophageal eosinophilia [1,2]. One group of patients exhibit marked esophageal eosinophilia (>15 eo/HPF), negative esophageal pH-monitoring studies and yet have clinicopathologic response to proton-pump inhibitor (PPI) treatment: this group is categorized as having PPI-responsive esophageal eosinophilia (PPI-REE) [1,3]. It is not certain whether those with PPI-REE are cases of GERD undiagnosed by pH-monitoring, EoE responding to PPI therapy as in-vitro studies suggest [4], or some combination thereof. GERD is orders of magnitudes more prevalent than EoE and thus misdiagnosed cases of GERD could have significant impact on any study of EoE patients [5,6]. Other groups have attempted to distinguish cases of PPI-REE and EoE, but failed to do so using clinicopathologic criteria [7,8]. This retrospective review of patients diagnosed with EoE aimed to differentiate PPI-REE and non-responsive patients, with an emphasis on prevalence of food allergy between the two groups.