What is Eosinophilic Esophagitis (EOE)?
Eosinophilic esophagitis (EoE) is a chronic, immune/antigen-mediated disease characterized clinically by symptoms of esophageal dysfunction and histologically by eosinophil-predominant inflammation isolated to the esophagus. 1
Core Definition
EoE represents a clinicopathologic condition requiring both clinical symptoms AND histologic findings for diagnosis—neither parameter should be interpreted in isolation. 1 The disease is triggered by exposure to food or aeroallergens, which induces a type-2 (allergic) immune response in the esophageal tissue. 1
Diagnostic Criteria
The diagnosis requires meeting all of the following criteria:
Clinical symptoms related to esophageal dysfunction 1
Histologic threshold: ≥15 eosinophils per high-power field (peak value) on esophageal biopsy 1, 2
Isolated to the esophagus: No involvement of stomach, small intestine, or colon (which would indicate eosinophilic gastroenteritis instead) 2
Exclusion of other causes of esophageal eosinophilia 1
Pathophysiology
EoE involves an antigen-driven immunologic process with multiple pathogenic pathways. 1 The disease develops through a dysregulated feed-forward cycle between the esophageal epithelium and immune system, where allergen-induced type-2 immune activation propagates impaired mucosal barrier integrity and allergic inflammation. 3 Genetic factors play a role, with polymorphisms in the thymic stromal lymphopoietin protein gene implicated in disease susceptibility. 1
Endoscopic Features
Characteristic findings include (though the esophagus can appear normal): 1, 2
- Rings (concentric)
- Linear furrows
- White plaques or exudates
- Edema or decreased vascularity
- Strictures or luminal narrowing
- Crepe-paper mucosa (fragile mucosa)
Natural History and Complications
EoE is a chronic disease requiring long-term management. 1 Untreated transmural inflammation leads to remodeling of the esophageal wall and smooth muscle hypertrophy, resulting in reduced esophageal wall compliance and contractility. 1 Progressive disease causes pathologic tissue remodeling with esophageal rigidity and loss of luminal diameter from strictures. 4 Diagnostic delay >2 years is associated with a 52% rate of fibrostenotic disease. 2
Treatment Options
Established first-line therapies include: 2
- Topical swallowed corticosteroids (fluticasone, budesonide)
- Dietary elimination (2-food, 4-food, or 6-food elimination diets)
- Proton pump inhibitor (PPI) therapy (PPI-responsive esophageal eosinophilia is now considered part of the EoE spectrum) 2
- Esophageal dilation for symptomatic strictures 1, 2
The treatment goal is to control inflammation to prevent fibrostenotic complications, not just symptom relief. 2 Disease remits with dietary exclusion, topical corticosteroids, or both. 1 Effective treatment can reverse tissue fibrosis in some patients and decrease the rate of food impactions. 4
Epidemiology and Prevalence
EoE affects both children and adults with increasing recognition and prevalence. 1 The estimated prevalence is approximately 34.4 per 100,000 people in Europe and North America. 5 Patients commonly have high rates of concurrent allergic conditions, especially food sensitization, compared with the general population. 1
Important Clinical Pitfalls
- Do not diagnose based on histology alone—both clinical symptoms and pathologic findings are required. 1
- PPI response should not exclude EoE diagnosis, as this is now recognized as part of the disease spectrum. 2
- Obtain adequate biopsies: at least 4 specimens from 2 or more esophageal levels, as inflammation is patchy. 1, 2
- Long-term follow-up is essential as EoE is a chronic condition that recurs without ongoing therapy. 1, 4