The Overlap of Allergic Disorders and Upper Gastrointestinal Symptoms: Beyond Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic disease which clinically presents with symptoms related to esophageal dysfunction, while pathologically it is characterized by eosinophilic infiltration of esophageal epithelium. Most patients with EoE present with food and/or inhalant allergy symptoms. The results of animal model studies and genetic studies, as well as the efficacy of elimination diets in managing the symptoms, suggest an atopic background of the disease. The aim of this study was to evaluate the prevalence of EoE in a group of patients with upper gastrointestinal symptoms and food and/or inhalant allergies and to assess the influence of drugs used in type I allergies on the results of endoscopic, histopathological, and immunohistochemical tests. <b>Methods</b>: This was a prospective observational study. Patients with inhalant/food allergies and upper esophageal symptoms constituted the study group while patients without allergies who were diagnosed with dyspepsia or irritable bowel syndrome constituted the control group. All study group subjects underwent allergy testing, including prick testing and blood tests. All participants underwent a gastroscopy with specimen collection. Esophageal specimens were stained for eotaxin-1 and desmoglein-1. <b>Results</b>: Based on histopathology results, eosinophilic esophagitis was found in 9 of the 73 patients from the study group. All patients with EoE presented with multimorbidity and were diagnosed with at least one allergic disease in addition to EoE. Positive staining for CCL-11 was found in 56 (78%) patients in the study group, including all patients with EoE while only 3 (17%) individuals from the control group showed positive staining. The presence of DSG-1 in esophageal specimens was detected in 6 (7%) subjects from the study group in contrast to 14 (78%) subjects from the control group. DSG-1 was not found in any of the specimens of patients diagnosed with EoE. <b>Conclusions</b>: EoE is a rare disease, usually accompanied by allergic multimorbidity. Positive staining for eotaxin-1 and negative staining for desmoglein-1 in patients with esophageal symptoms and allergies but who did not meet EoE diagnostic criteria could be indicative of subclinical course of the disease or a masking effect of corticosteroids. It is now vitally important for both researchers and practicing clinicians to recognize that eosinophilic esophagitis (EoE) is not a homogeneous disease but rather consists of multiple subtypes (phenotypes). The so-called "classic" form of EoE-defined by current diagnostic criteria as the presence of more than 15 eosinophils per high power field on histopathological examination-appears to represent only the tip of the iceberg. There is an urgent need for further research in order to refine endoscopic techniques, expand the scope of histopathological assessments, and identify novel biomarkers to better define the distinct phenotypes of eosinophilic esophagitis.