Eosinophilic gastroenteritis is a rare condition of the gastrointestinal tract. The infiltration of eosinophils into the mucosal, muscular, and serosal layers produces symptoms such as abdominal pain, dysphagia, diarrhea, failure to thrive, amenorrhea, protein and iron malabsorption, bleeding, and anemia. The initial diagnosis can be made through a detailed clinical assessment and laboratory studies showing eosinophilia. Imaging, microbiological, and histopathological studies, however, need to be conducted in order to rule out other more common causes of eosinophilia and confirm the presence of eosinophils in the epithelial lining of the intestines and stomach.
The features of eosinophilic gastroenteritis stem from the invasion of eosinophils and a subsequent inflammatory reaction involving the intestinal epithelium    . Although virtually any part of the gastrointestinal tract can be affected, the stomach and the proximal small intestine seem to be the most common sites  . The severity of symptoms somewhat depends on the depth of inflammation, but the non-specific complaints dominate the clinical presentation - abdominal pain (frequently accompanied by cramping), diarrhea, nausea with vomiting, and dysphagia  . Because the mucosal layer is universally affected, malabsorptive syndromes, particularly protein-losing enteropathy and iron deficiency, are a common finding, which often results in weight loss and anemia, respectively  . Lower gastrointestinal bleeding is present when eosinophilic gastroenteritis affects the colon  . A delayed onset of puberty, amenorrhea, failure to thrive, and growth retardation are notable manifestations in children and adolescents   . Ascites with very high peripheral eosinophilia are hallmarks of more severe forms of eosinophilic gastroenteritis in which subserosal layers of the intestinal wall are affected . In rare cases, accompanying disorders may include pancreatitis, acute appendicitis, and duodenal ulcers .
Because of the rare occurrence of eosinophilic gastroenteritis in clinical practice, the diagnosis may not be an easy one to make. In fact, studies show that up to 80% of patients experience symptoms for several years before the condition is recognized  . For this reason, it is necessary to perform a thorough workup in patients who report nonspecific gastrointestinal complaints, starting with a detailed patient history and a full physical examination. After the course of symptoms and their progression is noted, laboratory studies should be employed, revealing abundant peripheral eosinophilia with average counts of 2000/μL . Additional findings include anemia, hypoalbuminemia (as a result of fecal protein loss that can be tested through a 24h collection of alpha1-antitrypsin), steatorrhea, and high serum immunoglobulin E (IgE) levels . The differential diagnosis of peripheral eosinophilia is broad, which is why stool cultures (to rule out parasitic infections) and skin prick tests (to exclude allergies) are vital constituents of the workup . Computed tomography and ultrasonography are useful imaging studies (ascites and thickening of gastric folds are typically identified), but the nonspecific findings revealed during these procedures necessitates the use of endoscopy and subsequent histopathological examination  . Eosinophilic gastroenteritis is confirmed when eosinophils are visualized in the gastrointestinal tract and when all other possible causes of eosinophilia are excluded   .