Eosinophilic Esophagitis (EoE) is a chronic, immune-mediated allergic inflammatory disorder that is being diagnosed with increased frequency. Compelling evidence suggests the etiopathogenesis is allergic and the immune response is triggered by food antigens in most children afflicted with this condition. The literature characterization of EoE is descriptive and retrospective thus far. Our aim in collecting and analyzing data prospectively of all EoE patients seen at Ann & Robert H. Lurie Children's Hospital (Lurie Children's) is to better understand the etiology, pathogenesis and clinical presentation of EoE in patients to better delineate its association with other atopic conditions including reactive airway disease, seasonal allergies and atopic dermatitis. This will allow us to better evaluate the effectiveness of therapeutic strategies used to treat patients with EoE. In addition to collecting data prospectively, the investigators will also review the charts of EoE patients and those suspected of having EoE seen at Lurie Children's. This will allow us to also gather information on control patients, not diagnosed with EoE, who may not be followed in EoE clinic.

Eosinophilic esophagitis has recently emerged as a distinct clinical entity in children and adults. The diagnosis is based on the presence of at least fifteen eosinophils per high power field (hpf) in the esophageal biopsy in children pre-treated with at least eight weeks of adequate acid suppression therapy. The clinical spectrum of EoE varies by age and ranges from failure to thrive and food aversion in toddlers to GERD-like symptoms in school age children to solid food dysphagia and food impaction in adolescents. Although the elemental diet has proven to be more effective than other less restrictive elimination diets in treating EoE, the latter has practical advantages over elemental therapy. In contrast to diet-mediated treatments, topical and systemic corticosteroids are also used to manage EoE symptoms and studies are underway to establish the safety and efficacy of anti-interleukin-5 monoclonal antibodies. The natural history of EoE is not known and prospective studies are needed to understand the etiopathogenesis, distinguish it from other atopic conditions, determine optimal treatment therapies, and to validate noninvasive surrogate tests to monitor histological remission of this enigmatic disorder.

Health outcomes in children and adolescents related to EoE primarily focus on symptoms and histology. This does not take into consideration the health related quality of life (HRQOL), which may be conceptualized to include physical health, mental health, social functioning, role functioning, and general health perceptions. HRQOL has been shown to affect patient satisfaction with and adherence to treatment, and therefore long term outcomes.

The PedsQLTM 4.0 is a, self-administered, non-preference based generic instrument. It consists of a 23-item core measure of global health-related quality of life (HRQOL). The tool includes scales of physical, emotional, social and school function and is validated for children age 2-18 years. Multiple studies have demonstrated the reliability, validity and responsiveness of this instrument in healthy children and in children with chronic diseases. Even more recently developed is the PedsQLTM Eosinophilic Esophagitis Module, a disease-specific tool that has demonstrated excellent feasibility, reliability and validity in EoE patients.

Additionally the investigators are using the Pediatric Eosinophilic Esophagitis Symptom Severity Module, Version 2.0® in measuring patient-relevant outcomes. The 20 question survey was created in an effort to identify and uniquely measure relevant outcomes that patients with EoE and their families identified as important. Within the 20 questions, patient and family input is established from four major domains: dysphagia, gastrointestinal reflux disease (GERD), nausea/vomiting, and pain. A recent study found that the administration of this survey will yield results in the specific domains correlated to specific patient-reported symptoms.

Inclusion Criteria:

-Patients with an established diagnosis of EoE, based on endoscopy with biopsies with ≥15 eosinophils per hpf in esophageal biopsies after symptoms of esophageal dysfunction persist despite at least 6-8 weeks of appropriate acid suppression therapy.

OR

-Patients who are suspected of having EoE (presenting with symptoms of esophageal dysfunction non-responsive to appropriate proton pump inhibitor therapy for 6-8 weeks).

• Note: Patients suspected of having EoE but not diagnosed with EoE by endoscopy with biopsies will serve as control patients

Exclusion Criteria:

• Patients who do not consent to participate

Study population is determined through general GI and EOE specific clinics. Patients who are undergoing pre-diagnostic endoscopies to change of treatments are enrolled into this study.