What is the recommended diagnostic and treatment approach for a patient with lower esophageal squamocolumnar mucosa and mild eosinophilia (up to 11 eosinophils per high‑power field), where the differential includes reflux esophagitis versus eosinophilic esophagitis?

Diagnostic and Treatment Approach

This patient does NOT meet diagnostic criteria for eosinophilic oesophagitis and requires additional biopsies from multiple oesophageal sites before any definitive diagnosis or treatment can be initiated. 1

Why This Histology is Insufficient

The current finding of 11 eosinophils per high-power field falls below the diagnostic threshold of ≥15 eosinophils per 0.3 mm² (equivalent to one high-power field) required for eosinophilic oesophagitis 1. Additionally, only sampling the lower oesophagus is inadequate—at least six biopsies from different anatomical sites within the oesophagus are mandatory for proper diagnosis and follow-up 1.

This is a critical pitfall: eosinophilic oesophagitis can have patchy distribution, and sampling only the distal oesophagus may miss diagnostic areas in the proximal or mid-oesophagus. The pathologist's recommendation for mid-oesophageal sampling is therefore essential and evidence-based.

Immediate Next Steps

1. Repeat Endoscopy with Adequate Biopsy Protocol

• Obtain at least 6 biopsies from different oesophageal levels (proximal, mid, and distal oesophagus) 1
• Document endoscopic findings carefully: look for rings, furrows, white plaques/exudates, strictures, or a normal-appearing oesophagus 1
• Ideally, perform this endoscopy after withdrawing proton pump inhibitors for at least 3 weeks to obtain accurate baseline histology 1

However, there's an important nuance here: the 2022 BSG guidelines strongly recommend PPI withdrawal for accurate diagnosis 1, but the 2018 AGREE consensus removed the PPI trial requirement from diagnostic criteria 2. In real-world practice, if the patient is already on PPIs and symptomatic, proceeding with repeat endoscopy on therapy is acceptable, but document this clearly.

2. Clinical Context Assessment

Determine which diagnosis is more likely based on:

Features favouring eosinophilic oesophagitis:

• Male sex (75% of EoE patients) 3
• Dysphagia or food bolus obstruction 1
• History of atopy (asthma, allergic rhinitis, eczema, food allergies) 1, 3
• Younger age (children and young adults)
• Endoscopic findings: linear furrowing, white papules, rings, strictures 3

Features favouring reflux oesophagitis:

• Typical GERD symptoms (heartburn, regurgitation, chest pain) 1
• Hiatal hernia 4
• Older age
• Absence of atopic history
• Response to standard-dose PPI therapy

Critical point: Eosinophilic oesophagitis and GERD are NOT mutually exclusive and can coexist in the same patient (high-quality evidence) 1. This is a paradigm shift from older thinking.

Treatment Algorithm Based on Repeat Biopsy Results

If Repeat Biopsies Show ≥15 Eosinophils/HPF:

First-line treatment options (all have strong evidence):

1. Proton Pump Inhibitors 1

   • Twice daily dosing for 8-12 weeks minimum
   • Histologic remission rate ~45-50% 1, 5
   • Endoscopy with biopsy while on treatment is mandatory to assess response, as symptoms don't correlate with histological activity 1
   • If remission achieved, continue PPI for maintenance 1

2. Swallowed Topical Corticosteroids 1

   • Histologic remission rate 80-93% 5
   • Higher efficacy than PPIs but requires maintenance therapy due to high relapse rates after withdrawal 1
   • Maintenance therapy reduces risk of food bolus obstruction 1

3. Elimination Diets 1

   • Six-food elimination diet has highest remission rates (~60%) but lower compliance 1
   • Requires experienced dietitian support throughout elimination and reintroduction 1

4. Dupilumab (biologic)

   • Histologic remission rate ~60% 5
   • Consider for refractory cases

Treatment selection depends on:

• Patient preference and lifestyle
• Severity of symptoms
• Presence of strictures (may require dilation)
• Availability of dietitian support
• Cost considerations

If Repeat Biopsies Show <15 Eosinophils/HPF:

• Diagnose as reflux oesophagitis
• Treat with standard PPI therapy
• Consider pH monitoring if diagnosis remains uncertain despite adequate PPI therapy
• Re-evaluate if symptoms persist despite treatment

Critical Monitoring Point

Early diagnosis and treatment may prevent long-term complications including fibrosis and strictures requiring endoscopic intervention 1. Stricture risk increases approximately 5% per year of undiagnosed disease 5. This underscores why obtaining adequate biopsies now—rather than waiting—is essential for patient outcomes.

Common Pitfalls to Avoid

• Don't diagnose EoE with <15 eosinophils/HPF regardless of clinical suspicion
• Don't rely on single-site biopsies—EoE has patchy distribution
• Don't assume symptom improvement means histologic remission—always verify with repeat endoscopy and biopsy 1
• Don't dismiss the possibility of coexisting GERD and EoE 1
• Don't forget that high eosinophil counts can occur in GERD 6—clinical context matters