39.1 Most Interesting Information

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  This is a clinicopathological condition characterized by symptoms of esophageal dysfunction and dense esophageal epithelial eosinophilia (> 15 eosinophils per high-power field [eos/HPF]).

  
  
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  It’s an enigmatic disease that mechanically is defined as an antigen-driven condition limited to the esophagus. It is an eosinophil-predominant disorder with a T_h2-cytokine profile suggestive of other allergic disorders, such as allergic rhinitis, asthma, and atopic dermatitis.

  
  
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  Eosinophils reside in most of the gastrointestinal mucosa; however, they are not present in the normal esophageal epithelia.

  
  
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  Similar to the airway remodeling that can occur in chronic asthma, eosinophilic esophagitis (EoE) can result in increased subepithelial collagen deposition, angiogenesis, and smooth muscle hypertrophy. Complications can result in esophageal remodeling with strictures and food impactions.

39.2 What Do We Know?

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  Eosinophilic esophagitis is an allergen-driven disease.

  
  
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  The most common triggers for EoE are foods. This is especially true for milk, egg, soy, and wheat.

  
  
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  T_h2 inflammation via cytokines predominates the pathogenesis of EoE.

  
  
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  Skin prick testing may be useful in children with EoE, but does not routinely demonstrate triggering food allergens in adults.

  
  
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  Oral immunotherapy to both foods and pollens may trigger EoE.

39.3 What Is Still Unknown at This Time?

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  What is the best way to test for potential allergens that may be triggering EoE?

  
  
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  Are there allergen-specific T-cells in the esophagus that could be potential targets for treatment?

  
  
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  Can immunotherapy be a treatment option for EoE?

  
  
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  Will targeted modulation of the immune system be a therapeutic treatment option for EoE in the near future?

39.4 Prevalence

Eosinophilic esophagitis is a chronic, immune/antigen-mediated esophageal disease characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation. Eosinophilic esophagitis is defined as a clinicopathologic diagnosis characterized by a localized eosinophilic inflammation of the esophagus (with no other gastrointestinal involvement), symptoms of esophageal dysfunction, the presence of 15 or more eosinophils in the most severely involved HPF isolated to the esophagus, and failure to respond to adequate proton-pump inhibitor (PPI) therapy. The Updated Consensus Recommendations for Children and Adults stresses that EoE is a clinicopathologic disease; both features are needed to make a diagnosis of EoE.

Estimates suggest that in the United States there are about 40 to 90 cases of EoE per 100,000 persons. The pediatric incidence of EoE approximates 1 per 10,000 population. Eosinophilic esophagitis can affect patients of any age. There is suggestion of a bimodal peak age of onset. In children, there is no peak after infancy whereas in adults, the peak incidence is from 30 to 40 years of age.

There is a strong association of EoE with atopic diseases. Patients with EoE have a higher rate of atopy than the general population. Majority (50−80%) of patients with EoE have other associated atopic conditions such as asthma, atopic dermatitis, and allergic rhinitis. Eosinophilic esophagitis shares many common immunologic features with other atopic diseases. Besides local eosinophilia, EoE also demonstrates impaired barrier function with infiltration of T-helper type 2 cells, basophils, mast cells, and type 2 innate lymphoid cells.

39.5 Clinical Presentation

The symptoms of EoE can include epigastric pain and vomiting but may also resemble the symptoms of gastroesophageal reflux disease (GERD). However, obstructive symptoms, such as dysphagia and food impactions, are typical in EoE and not in GERD. The predominant presenting symptom of EoE varies by age. Young children are more likely to present with feeding difficulties, failure to thrive, and classic GERD symptoms (epigastric pain) whereas older children are more likely to present similar to adults with dysphagia-type complaints and possible food impactions. It may be difficult for a young child to vocalize that they are having difficulty swallowing. They may exhibit refusal behavior and prolonged chewing. Even an older school-aged child or teenager may not complain of outright dysphagia but may exhibit some compensatory behaviors including taking small bites, drinking after each bite, or avoiding problematic foods such as meat and bread.

Classic symptoms of EoE in adults include dysphagia for solids and food impactions. The dysphagia may be either intermittent or chronic and is present in 25 to 100% of adult patients with EoE. A variety of other symptoms are also encountered, some of which are uncommon and not widely recognized. Although the most common symptom in adults is dysphagia, it is important to note that nonspecific symptoms such as nausea, vomiting, and abdominal pain may be the only clinical manifestation of EoE in selected adults. Food impaction can also occur in adults with EoE. It can either precede the diagnosis of EoE or be an ongoing manifestation of the disease. Food impaction warranting endoscopic removal is encountered in 33 to 54% of adult patients with EoE.