Eosinophilic Gastroenteropathi... Health Article

Definition

Eosinophilic gastroenteropathies are gastrointestinal (GI) diseases (enteropathies) in which one or more layers of the GI tract (most commonly the stomach and small intestine) are selectively infiltrated with a type of white blood cell called eosinophils, as part of an allergic response.

Description

Eosinophilic gastroenteropathies are characterized by the accumulation of an abnormally large number of eosinophils (eosinophilic infiltration) in one or more specific places anywhere in the digestive system and associated lymph nodes resulting in nausea, difficulty swallowing, abdominal pain, vomiting and diarrhea, excessive loss of proteins in the GI tract, and failure to thrive. All gastroenteropathies are characterized by the presence of abnormal GI symptoms, eosinophilic infiltration in one or more areas of the GI tract, and the absence of an identified cause for the formation of an abnormally large number of eosinophils in the blood (eosinophilia). Some patients also suffer loss of protein from the body that often results in low blood levels of albumin and total protein (protein-losing enteropathy) due to increased GI tract permeability. As the GI tract wall becomes infiltrated with large numbers of eosinophils, its normal architecture is disrupted, and so is its function. Eosinophils are immune system white blood cells that destroy parasitic organisms and play a major role in allergic reactions. For this reason, the gastroenteropathies are often considered as food-related gastrointestinal allergy syndromes.

Eosinophilic gastroenteropathies have a specific name corresponding to the area of the digestive system where the highest numbers of eosinophils are found. They include the following:

• eosinophilic gastroenteritis (EG), in which eosinophilic infiltration occurs in one or more layers of the stomach and/or small intestine
• eosinophilic esophagitis (EE), in which eosinophilic infiltration is confined to the muscular tube that carries food from the throat to the stomach (esophagus)
• eosinophilic colitis (EC), in which the infiltration is confined to the large intestine (colon)
• eosinophilic duodenitis (ED), in which the infiltration is confined to the small intestine

Eosinophilic gastroenteritis (EG) is the best characterized gastroenteropathy. It is classified according to the layer of the GI tract involved, and mixed forms also occur. The walls of the GI tract have four layers of tissue, called mucosa, submucosa, muscularis externa, and serosa. The innermost layer is the mucosa, a membrane that forms a continuous lining of the GI tract from the mouth to the anus. In the large bowel, this tissue contains cells that produce mucus to lubricate and protect the smooth inner surface of the bowel wall. Connective tissue and muscle separate the muscosa from the second layer, the submucosa, which contains blood vessels, lymph vessels, nerves, and glands. Next to the submucosa is the muscularis externa, consisting of two layers of muscle fibers, one that runs lengthwise and one that encircles the bowel. The fourth layer, the serosa, is a thin membrane that produces fluid to lubricate the outer surface of the bowel so that it can slide against adjacent organs. The different types of EG are:

• Pattern I eosinophilic gastroenteritis: Children affected with Pattern I EG have extensive infiltration of eosinophils in the area below the submucosa and muscularis layers. It is more commonly seen in the stomach (gastric antrum) but may also affect the small intestine or colon. Patients typically have intestinal obstruction. Cramping and abdominal pain associated with nausea and vomiting occur frequently. Food allergy and past history of allergy are less common in these patients than in patients with Pattern II EG.
• Pattern II eosinophilic gastroenteritis: In this the most prevalent form of EG, extensive infiltration of eosinophils occurs in the mucosal and submucosal layers. These patients have colicky abdominal pain, nausea, vomiting, diarrhea, and weight loss. Infants with Pattern II EG also commonly have a history of allergy. The condition may also be associated with protein-losing enteropathy, low levels of iron in the blood serum or in the bone marrow (iron-deficiency anemia), or impaired absorption of nutrients by the intestines (malabsorption). Growth retardation, delayed puberty, or abnormal menstruations has also been reported in children and adolescents with Pattern II EG.
• Pattern III eosinophilic gastroenteritis: This least common form of eosinophilic gastroenteropathy involves the serosal layer and the entire GI wall is usually affected. Its inflammation leads to an accumulation of fluid in the abdomen (ascites). This fluid contains many eosinophils and can infiltrate the membrane of the lungs (pleural effusion). A history of allergy also appears to be common in this group. Symptoms may include chest pain, fever, shortness of breath, and limited motion of the chest wall.

Eosinophilic esophagitis (EE) is characterized by the abnormal accumulation of eosinophils localized in the esophagus. In EE, high levels of eosinophils are detected in the esophagus but not in any other parts of the digestive tract. The presence of the eosinophils in the esophagus causes inflammation of its walls, which makes digestion extremely painful. Unlike that of normal children, the esophagus of an individual with EE does not have a smooth, uniform pink surface but displays lines (furrowing) and white patches. Children with EE have classic signs of gastroesophageal reflux (abdominal pain, difficulty swallowing, and vomiting) but fail to respond to antireflux medications. The danger of failing to diagnose this disorder is that children may be referred for unnecessary surgery because of their reflux symptoms.

Eosinophilic colitis (EC) is characterized by eosinophilic infiltration localized only in the large bowel, resulting in fever, diarrhea, bloody stools, constipation, obstruction/strictures, acute abdominal pain, and tenderness often localized in the right lower abdomen. EC often follows the onset of EG.

Eosinophilic duodenitis (ED) is characterized by eosinophilic inflammation of the small bowel that results in the production of leukotrienes, substances that participate in defense reactions and contribute to hypersensitivity and inflammation. Malabsorption of nutrients always results along with severe cramping, bowel obstruction, and intestinal bleeding with passage of bloody stools.