1Overview

Eosinophilic esophagitis (EoE) is an inflammatory disease of the esophagus.
It has increasingly become recognized in children and adults for the last ten years.
The disorder is sometimes termed as “the asthma of the esophagus” because it shares many of the clinical signs and pathological symptoms of asthma.

Eosinophils are a type of white blood cells that are present throughout the gastrointestinal tract. This is due to the fact that the GI tract is continuously exposed to foods, toxins, allergens, and pathogens. In healthy individuals, eosinophils cannot be found in the esophagus. However, in EoE, eosinophils are found in the esophagus, which contributes to inflammation and tissue damage. EoE is defined as a pathologic disorder that is characterized by the presence of more than 15 eosinophils per high power field.
This is found in one or more biopsies of the esophagus and gastrointestinal reflux disease (GERD) is generally absent.

The prevalence of EoE remains unclear because of the lack of knowledge surrounding it. Current prevalence estimates range from 1-4 per 10,000 persons in children and adolescents up to 19 years of age. However, recent studies have shown that the prevalence of EoE is increasing.

2Symptoms

Typically, the onset of EoE is during childhood, however, the disease can also be found among all age groups. The symptoms of EoE tend to vary with the age group.
In infants and toddlers, clinical manifestations usually include refusing food, vomiting, choking with meals, and sometimes, failure to thrive. In school-aged children,
the predominant features include difficulty swallowing (dysphagia), choking, food impactions, and gagging with meals, especially if the food is coarse in texture.
In this population, other symptoms include abdominal/chest pain, regurgitation,
and vomiting. Children with EoE often have learned to compensate for these problems by eating slowly, taking small bites, or chewing excessively. They may also drink excessively with meals in order to lubricate the food. They may also use a lot of sauces for this purpose.

In adults, the predominant symptoms are dysphagia. However, heartburn and food avoidance may also be observed. Adults presenting with EoE tend to have more food impactions compared to other age groups because of the long-standing condition and the scarring that resulted.

Esophageal abnormalities may also be observed, such as the presence of the Schatzki ring just above the junction between the stomach and the esophagus. Achalasia may also be present in some cases, which is a motility disorder of the esophagus characterized by regurgitation and difficulty swallowing.

However, it is important to note that some patients with EoE are asymptomatic and diagnosis should be based on a careful history of the patient as well as endoscopic findings. It may also be suspected upon evidence of food impaction even when other symptoms are absent. Although many of the symptoms overlap with the symptoms of GERD, patients with EoE often do poorly on acid-suppression therapy. Up to 75% of patients with EoE have a family history of atopy.

3Causes

 The causes of EoE remain unclear, but they are though to be due to the action of T helper cells (Th)-2 type immune responses. These immune responses are typical of other disorders where allergy is a problem. In particular, elevated levels of Th2 cytokines IL-4, IL5, and IL-3, in addition to mast cells, have been detected in the esophagus of people with EoE. These cytokines appear to play an important part in the recruitment and activation of eosinophils to the esophagus. Furthermore, there is new evidence suggesting that genetic predisposition for EoE is present. The gene for eotaxin-3, which is a chemokine involved in promoting the adhesion and accumulation of eosinophils, was found to be increasingly expressed in patients with EoE.

EoE is thought to be a mixed immunoglobulin (Ig)E- and non-IgE-mediated response to food, as well as environmental allergens. The reaction mediated by IgE are immediate hypersensitivity responses that occur rapidly after ingesting a food with an allergen
Non-IgE-mediated allergic disorders, in contrast to this, are characterized by a delayed onset after ingestion. They also come with potentially more chronic symptoms related to the disease. The majority of patients with EoE were found to have positive results from the skin prick test and atopy patch tests.

4Risk Factors

Several risk factors exist for EoE. One of them is exposure to pollen and other allergens that are carried in the air. A correlation was found between the number of eosinophils seen upon biopsy, pollen counts, and clinical symptoms severity. Other studies have found that the rate of EoE increases along with fluctuations in the daily average pollen counts. Thus, living in places where the pollen count is high is a risk factor for EoE.

Living in arid and cold climates appears to be a risk factor for EoE. Living in the suburbs is another risk factor. Studies have shown that those who live in the suburbs are 2.08 times more likely to have EoE. Clinical features may also vary according to the area.
For example, urban patients were more likely to present to the doctor with dysphagia and rural patients were more likely to present with heartburn and reflux.

The season also plays a role and is another risk factor for the development of EoE. EoE is more commonly diagnosed in spring and summer compared to fall or winter months.

5Complications

EoE can have many complications. One of these is fibrostenotic complications, which are composed of esophageal strictures as well as the narrow-caliber esophagus. In these cases, esophageal dilation is the preferred treatment. Strictures and stenosis can make it hard to swallow, which may lead to malnutrition in some cases. The lumen of the esophagus may also narrow in EoE, which makes it difficult to ingest food. Strictures have been reported in 57% of patients with EoE. Furthermore, studies suggest that strictures can form in the early stages of the disease rather than as a late consequence.

A serious complication is an esophageal perforation. This complication can cause extensive bleeding and hemorrhage within the body and should be addressed as soon as possible.

EoE is also associated with Barrett’s esophagus, which is a condition wherein the cells of the esophagus have changed and can become cancerous. Cancers of the esophagus are fatal and they decrease the patient’s quality of life.

Food impaction occurs in about 60% of patients with EoE. This is generally caused by eating dry rice and meats. It is an obstructive complication and can persist for hours.

Secondary GERD can also occur because chronic inflammation can lead to the dysfunction of the lower esophageal sphincter (LES). Infections may also occur. In particular, candidiasis occurs spontaneously in patients with EoE.

6Diagnosis

Currently, the only way to diagnose EoE is by performing an upper endoscopy with biopsy. During endoscopy, a thin tube with a camera is inserted into the esophagus while the patient is asleep. Biopsies taken from the lining of the esophagus (mucosa) are then taken to a pathologist for examination. Biopsy specimens should be obtained regardless of the appearance of the mucosa. At least four biopsies are required to detect EoE with a high sensitivity.GERD must, however, be ruled out. It is recommended that acid-suppressive therapy

GERD must, however, be ruled out. It is recommended that acid-suppressive therapy is tried from 6-8 weeks before performing an endoscopy. Then, a barium swallow should be conducted to rule out a small-caliber esophagus.

Although the endoscopic examination may be normal, the endoscopic features of EoE have been well-documented. These include linear furrowing, concentric rings, eosinophilic abscesses, Schatzki ring, superficial mucosal tears, and a small-caliber esophagus. It should be noted that, while endoscopic findings are helpful for identifying patients with EoE, these are not definitive diagnostic tools for the disease.

In addition to these, a thorough personal and family history of the patient should be taken in order to check for allergies. Testing for skin sensitization may be considered through the use of skin prick tests or blood testing. Atopy patch testing is a newer approach that is being used to detect EoE.

7Treatment

The treatment strategies for addressing EoE fall into three categories: 1) dietary modifications to avoid triggers; 2) pharmacologic therapy; and 3) dilatation of the esophagus. However, it is important to note that most of these regimens were based on case series studies and there has been limited testing of these regimens through randomized controlled trials.

Dietary modifications consist of removing all sources of allergens from the diet.
The patient can be placed on an amino acid-based formula for nutritional support. Assuming that there is a favorable response, 1 new food per week can slowly be introduced into the diet. Then, endoscopy should be repeated.

Pharmacologic management of EoE includes corticosteroids, biologic agents, and leukotriene modifiers. Oral corticosteroids result in the improvement of symptoms of EoE.

Esophageal dilation is useful for relieving dysphagia, however, it does not address the underlying disease processes. Therefore, the majority of patients who have elected to undergo this procedure develop recurrent symptoms. Furthermore, endoscopic dilation has been associated with mucosal tearing and perforation.