Eosinophilic Gastritis (EG) is a chronic inflammatory disorder and a rare form of Eosinophilic Gastrointestinal Diseases (EGIDs). This condition specifically targets the stomach, causing persistent inflammation and injury. EG is characterized by the abnormal accumulation of eosinophils—a specialized type of white blood cell—within the stomach lining.
Defining Eosinophilic Gastritis
Eosinophils are immune cells that normally reside in the digestive tract in low numbers, defending the body against parasitic infections and contributing to allergic responses. In EG, a dysregulated immune response causes these cells to migrate and gather excessively in the stomach wall, often triggered by an allergic response. Once activated, eosinophils release toxic proteins and enzymes that damage the surrounding stomach tissue, leading to chronic inflammation.
The degree of inflammation and symptoms relate directly to the depth of eosinophil infiltration into the stomach wall layers. If infiltration is limited to the superficial mucosa, patients may experience symptoms like nausea and abdominal pain. A deeper accumulation, involving the submucosa or the muscle layer, can cause more severe issues, such as thickening of the stomach wall or obstruction.
Identifying the Underlying Causes
The precise cause of EG is often not fully understood, and in some cases, the condition is considered idiopathic, meaning without a known origin. However, EG is strongly linked to an immune-mediated or allergic response, suggesting the body mistakenly targets harmless substances. The influx of eosinophils is often triggered by exposure to certain food or environmental allergens, which activates a Type 2 immune pathway involving specific cytokines.
EG has a significant association with other atopic or allergic disorders, such as asthma, eczema (atopic dermatitis), and allergic rhinitis (hay fever). Approximately half of people diagnosed with EG also have a history of these hypersensitivity conditions. The most common food allergens implicated include milk, soy, wheat, eggs, nuts, and fish or shellfish.
People with a personal or family history of allergic conditions have a higher risk of developing this specific type of gastrointestinal inflammation. While the immune response is localized to the stomach, the underlying predisposition to allergies is systemic.
Diagnosis and Confirmation
Diagnosing EG requires clinical suspicion, physical examination, and specialized testing to rule out other causes of tissue eosinophilia. Because EG symptoms, such as abdominal pain, nausea, and vomiting, overlap with many other common digestive disorders, diagnosis can be challenging and often delayed. Obtaining a tissue sample for microscopic analysis is the most important step in confirmation.
A healthcare provider performs an upper endoscopy, inserting a thin, flexible tube with a camera into the stomach and often into the first part of the small intestine. During this procedure, the physician looks for visible signs of inflammation, such as redness or swelling, and takes small tissue samples, known as biopsies, from the stomach wall. A pathologist then examines these samples to count the number of eosinophils present under the microscope.
An EG diagnosis is confirmed when biopsy samples show an abnormally high concentration of eosinophils in the stomach tissue, along with the patient’s characteristic symptoms. There is no single, universally agreed-upon threshold for what constitutes an elevated number of eosinophils in the stomach. Therefore, the final diagnosis requires the exclusion of other conditions that can also elevate eosinophil counts, such as infections, parasitic disease, or certain drug reactions.
Current Treatment Approaches
The management of EG focuses on two primary strategies: reducing stomach inflammation and identifying and eliminating specific triggers. Treatment is usually ongoing, as EG is a chronic condition without a definitive cure. Due to the strong link to allergic triggers, dietary management is often the first-line approach.
Dietary strategies include elimination diets, where common food allergens are systematically removed and then gradually reintroduced to pinpoint the culprits. For more severe cases, an elemental diet may be prescribed, replacing all food with a specialized liquid formula containing only pre-digested amino acids. This approach ensures complete nutrition while completely avoiding potential food antigens.
Pharmacological management typically involves corticosteroids to suppress the immune response and reduce inflammation. Systemic steroids, such as prednisone, are often used to quickly induce remission in severe cases, but their long-term use is limited by potential side effects. Emerging therapies include biologic medications, which are targeted drugs that block specific immune pathways, such as those involving Interleukin-4 and Interleukin-13.