Eosinophilic oesophagitis, which is sometimes abbreviated to EoE in American publications, is an allergic inflammatory condition of the oesophagus that involves eosinophils. It was first discovered as a clinical entity around 20 years ago but has only recently become recognised on a broader scale.

It occurs most commonly in middle age (average age at diagnosis is 30-50 years). It is more common in men with a 3:1 male-to-female ratio is 3:1. It is commonly associated with allergic conditions, in particular, atopy.

The clinical features of eosinophilic oesophagitis depend upon the age of the patient.

Adults tend to present with the following features:

• Dysphagia
• Food bolus obstruction
• Heartburn
• Chest pain

Children tend to present with the following features:

• Failure to thrive
• Food refusal and difficulty feeding
• Vomiting
• Abdominal pain

The key to diagnosis is in considering the possibility of eosinophilic oesophagitis in patients presenting with persistent heartburn and/or difficulty swallowing in patients with a history of allergy or atopic disease.

Diagnosis relies on demonstrating more than 15 eosinophils per high-power field on microscopy of an oesophageal biopsy. Allergy testing is ineffective as the condition is not IgE-mediated.

Approximately 1/3 of patients are ‘PPI responsive’. If an endoscopic biopsy confirms the presence of eosinophils, then a trial of 8 weeks of a PPI can be undertaken. After the 8-week trial, a repeat endoscopy and biopsy should be performed to look for persistent eosinophils. The 1/3 of patients that respond to PPIs are diagnosed with ‘PPI responsive oesophageal eosinophilia. If there is no resolution, a diagnosis of ‘true eosinophilic oesophagitis’ is made.

There are two other main treatment options for eosinophilic oesophagitis:

1. Dietary manipulation

Dietary manipulation can be effective in both children and adults. It can be used as an initial treatment or as an adjunct to pharmacological therapy. The six most commonly implicated food groups are cow’s milk, wheat, egg, soy, peanut/tree nut, fish/shellfish. There are four main approaches:

• Elemental diet: this involves taking an amino acid mixture for six weeks. The mixture is often considered unpalatable, and compliance is often poor, but considerable improvement in symptoms and the histological picture has been noted. This will resolve symptoms in >90% though.
• Six food elimination diet (SFED) – exclusion of the six food groups listed above. Remission seen in >70%.
• Four food elimination diet (FFED) – uses the same principle but patients are allowed to eat nuts and fish/shellfish. Remission seen in >50%.
• Step-up approach – starts with just milk and wheat exclusion, then steps up to the FFED and then the SFED if unsuccessful. Remission seen in around 40% initially.

2. Topical corticosteroids

Patients can also swallow ‘inhaled’ corticosteroids, e.g. fluticasone or aqueous nebuliser solutions (e.g. budesonide mixed with a sugary syrup). This coats the oesophagus with the corticosteroid without risking the side effects of taking oral corticosteroids. 50-80% will have histological remission with this strategy. Oral candidiasis is a significant problem, with around 30% suffering this side effect.

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