Eosinophilic esophagitis (EoE) has been defined as a ‘chronic, immune/antigen-mediated, esophageal disease, characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation'. A peak value of ≥15 eosinophils/high power field has been defined as histologic diagnostic cutoff. Other conditions associated with esophageal eosinophilia, such as gastro-esophageal reflux disease, PPI-responsive esophageal eosinophilia or Crohn's disease, need to be ruled out before EoE can be diagnosed. Males are affected more frequently than females and most of the patients have concomitant allergies. Currently, the EoE prevalence is about 1 of 2,000 inhabitants in Westernized countries. The first EoE patients were described only 2 decades ago. Despite this short period, considerable progress has been made regarding the understanding of the pathophysiology, natural history, assessment of disease activity and with respect to evaluating different therapeutic options. Untreated EoE can lead to esophageal remodeling with reduced compliance and stricture formation, which represents the main risk factor for food bolus impactions. The therapeutic options can be summarized with the 3 D's, which stand for drugs, diets and dilation. Of note, as of yet, there is no EoE-specific drug that has been approved by regulatory authorities. This is, among other reasons, related to the lack of validated outcome measurement instruments until recently. Swallowed topical steroids such as budesonide or fluticasone represent the standard of care for treating symptomatic pediatric and adult EoE patients with inflammatory activity. Several trials have already evaluated different biologic therapies, such as anti-interleukin-5 or anti-IgE. Further studies are on the way. As a non-pharmacologic alternative, different dietary regimens exist. Dilation can offer long-lasting symptomatic response in case of stricturing EoE but does not have any impact on the underlying inflammation. This review highlights the latest insights regarding pathophysiology and its impact regarding current and future therapeutic strategies.

Keywords:
Eosinophilic esophagitis, PPI-responsive esophageal eosinophilia, Eosinophils, Budesonide, Fluticasone propionate, Elimination diet, Dilation, Pathogenesis
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