How is eosinophilic esophagitis diagnosed?

How to Diagnose Eosinophilic Esophagitis

Eosinophilic esophagitis is diagnosed when a patient has symptoms of esophageal dysfunction (dysphagia, food bolus obstruction) AND esophageal biopsies show ≥15 eosinophils per 0.3 mm² (high-power field) after comprehensive assessment to exclude other causes of esophageal eosinophilia. 1

Clinical Presentation: Who to Suspect

Adults

• Dysphagia for solid foods (most common)
• Food bolus obstruction (strongly associated with EoE)
• History of atopy (asthma, allergic rhinitis, atopic dermatitis)
• Male predominance (75% of cases) 2

Children

• Symptoms are non-specific and age-dependent 1
• Feeding difficulties, vomiting, abdominal pain in younger children
• Dysphagia in adolescents
• Any child with upper GI symptoms undergoing endoscopy should have esophageal biopsies taken 1

When to Perform Endoscopy with Biopsies

Strong Indications (High-Grade Evidence):

Adults:

• Dysphagia or food bolus obstruction (even with normal-appearing esophagus) 1
• Endoscopic signs: linear furrows, white plaques/exudates, concentric rings, strictures, edema 1, 3

Children:

• All children undergoing endoscopy for upper GI symptoms 1
• PPI-refractory GERD symptoms 1

When NOT to Scope:

• Adults with typical GERD symptoms refractory to PPIs without dysphagia or atopy (low EoE prevalence in this group) 1

Critical Pre-Endoscopy Preparation

Withdraw PPIs for at least 3 weeks before endoscopy and biopsy to ensure accurate diagnosis 1. This is a strong recommendation despite very low evidence quality, as PPIs can reduce esophageal eosinophilia and mask the diagnosis.

Important caveat: The 2018 international consensus 4 removed the PPI trial requirement, recognizing that PPIs are a treatment for EoE rather than a diagnostic exclusion criterion. EoE and GERD can coexist 1.

Biopsy Protocol (Critical for Diagnosis)

Take at least 6 biopsies from different anatomical sites within the esophagus 1:

• Sample both proximal and distal esophagus (minimum 2 sites)
• Combine targeted biopsies (from visible abnormalities like furrows, white spots) with non-targeted biopsies 1
• This approach yields 97-100% diagnostic sensitivity 1

Why multiple biopsies matter: Eosinophilic infiltrate is patchy and can be easily missed with fewer samples 1.

Histologic Diagnostic Criteria

Primary criterion:

• ≥15 eosinophils per 0.3 mm² (equivalent to one high-power field) in ANY biopsy specimen 1, 4
• Report the peak eosinophil density (highest count in any single field) 1

Supporting histologic features (should accompany eosinophilia) 1:

• Basal cell hyperplasia
• Edema (spongiosis)
• Eosinophil microabscesses
• Eosinophil layering
• Eosinophil degranulation
• Subepithelial sclerosis

Differential Diagnosis to Exclude

Before confirming EoE, rule out other causes of esophageal eosinophilia 4:

• GERD (typically <5 eosinophils/hpf, but can overlap)
• Eosinophilic gastroenteritis
• Achalasia
• Connective tissue disorders
• Drug hypersensitivity
• Infection (parasitic)
• Crohn's disease

Key point: EoE and GERD are NOT mutually exclusive and can coexist 1, 4.

When Initial Biopsies Are Non-Diagnostic

If high clinical suspicion persists but initial histology is negative:

• Repeat endoscopy with adequate biopsies (at least 6 from multiple sites) 1
• Particularly if there were suggestive endoscopic features or typical symptoms

Consider EoE variants if symptoms persist with few/no eosinophils 5:

• EoE-like esophagitis
• Lymphocytic esophagitis
• Nonspecific esophagitis
• These may represent a spectrum disorder with eventual progression to classic EoE

Special Situations

Food Bolus Obstruction

• Urgent gastroenterology referral and endoscopy on next available list (or immediate emergency depending on presentation) 1
• Take biopsies at index endoscopy to diagnose EoE 1
• If spontaneous resolution occurs, still book endoscopy and outpatient review 1

Pediatric Considerations

• Lower threshold for biopsy in children with any upper GI symptoms 1
• Mandatory endoscopy for PPI-refractory symptoms 1

Common Pitfalls to Avoid

1. Insufficient biopsies: Taking <6 biopsies significantly reduces diagnostic yield
2. Single-site sampling: Missing patchy distribution of eosinophils
3. Not withdrawing PPIs: Can mask diagnosis by reducing eosinophil counts
4. Assuming GERD excludes EoE: These conditions frequently coexist
5. Ignoring normal-appearing mucosa: Up to 10% of EoE cases have normal endoscopy; always biopsy if symptoms suggest EoE 1
6. Variability in microscope fields: Ensure pathologist reports eosinophils per 0.3 mm² for standardization 1

Diagnostic Algorithm Summary

1. Identify clinical suspicion: Dysphagia, food impaction, atopy, or pediatric upper GI symptoms
2. Withdraw PPIs for ≥3 weeks (if safe to do so)
3. Perform endoscopy with systematic biopsy protocol (≥6 biopsies, multiple sites)
4. Confirm histology: ≥15 eosinophils/0.3 mm² plus supporting features
5. Exclude alternative diagnoses through comprehensive assessment
6. If negative but high suspicion: Repeat endoscopy with adequate sampling

Early diagnosis and treatment may prevent long-term complications including fibrosis, strictures, and recurrent food impactions requiring endoscopic intervention 1, 6.