What is Eosinophilic Esophagitis (EOE)?
Eosinophilic esophagitis (EoE) is a chronic, immune/antigen-mediated disease of the esophagus characterized by symptoms of esophageal dysfunction (dysphagia, food impaction) and histologically by eosinophil-predominant inflammation with ≥15 eosinophils per high-power field on esophageal biopsy. 1
Core Definition and Diagnostic Criteria
EoE is fundamentally a clinicopathologic entity requiring both clinical symptoms AND histologic findings for diagnosis—neither alone is sufficient. 1
Clinical Features:
- Adults: Dysphagia and food impaction are the hallmark symptoms 1, 2
- Children: Feeding problems, vomiting, and abdominal pain predominate 1, 3
- Patients often develop coping mechanisms including cutting food into small pieces, extensive chewing, lubricating foods with liquids, and avoiding textured foods like meats 1
Histologic Criteria:
- ≥15 eosinophils per high-power field (or ≥15 eosinophils/0.3 mm² or >60 eosinophils/mm²) on esophageal biopsy is the diagnostic threshold 1, 4, 5
- Biopsies must be taken from multiple levels (both proximal and distal esophagus) as inflammation can be patchy 1, 6
- The diagnosis requires exclusion of other causes of esophageal eosinophilia, particularly gastroesophageal reflux disease and achalasia 2, 3
Pathophysiology
EoE represents an antigen-driven immunologic process involving multiple pathogenic pathways, typically triggered by food or aeroallergens that induce a type-2 (allergic) response. 1 Genetic susceptibility has been identified, including polymorphisms in the thymic stromal lymphopoietin protein gene. 1
Endoscopic Findings
The esophagus may appear normal or demonstrate characteristic features: 1, 5
- Edema (swelling of esophageal mucosa)
- Rings (fixed concentric rings, also called "corrugated rings" or "trachealization")
- Exudates (white plaques or patches)
- Linear furrows (vertical lines)
- Strictures (narrowing of the esophageal lumen) 1, 2
Disease Progression and Complications
Untreated transmural inflammation leads to esophageal remodeling with smooth muscle hypertrophy, resulting in reduced esophageal wall compliance and contractility. 1 This progressive fibrosis causes:
- Esophageal rigidity
- Loss of luminal diameter
- Stricture formation
- Increased risk of food impactions 5, 7
Recent data demonstrate an increased risk for achalasia in patients with EoE. 1
Epidemiology and Prevalence
EoE affects an estimated 34.4 per 100,000 people in Europe and North America, with rapidly increasing incidence and prevalence. 2, 3 The disease affects both children and adults, with higher prevalence in Western countries. 7, 6
Allergic Associations
Patients with EoE have high rates of concurrent allergic conditions, especially food sensitization, compared with the general population. 1 An allergy evaluation is warranted in patients diagnosed with EoE. 1
Treatment Options
Proven therapeutic approaches include: 1
- Proton pump inhibitors (PPIs): First-line therapy with 41.7% histologic response rate 2, 6
- Topical corticosteroids (fluticasone, budesonide): 64.9% histologic remission rate 2, 3
- Dietary elimination therapy: Ranging from 2-food (43% remission), 4-food (60% remission), to 6-food elimination (79% remission) 8
- Esophageal dilation: Reserved for symptomatic strictures 5, 3
Important caveat: EoE is a chronic disease requiring long-term maintenance therapy to avoid disease recurrence and complications. 5, 3 Effective treatment can reverse tissue fibrosis in some patients and decrease the rate of food impactions. 5
Critical Diagnostic Pitfall
A subset of patients with esophageal eosinophilia respond to PPI therapy alone, termed "PPI-responsive esophageal eosinophilia"—the pathophysiology of this phenotype remains unclear and represents an area of ongoing investigation. 1