Eosinophilic Colitis (EC) is a relatively rare inflammatory gastrointestinal disorder affecting the large intestine, or colon. The condition is named for eosinophils, white blood cells normally involved in fighting parasites and regulating allergic responses. In EC, an abnormally high number of these cells accumulate within the colon wall, triggering chronic inflammation. This infiltration causes irritation and damage, leading to colitis symptoms. EC is one of the Eosinophilic Gastrointestinal Diseases (EGIDs), which can affect any part of the digestive tract.
Defining the Condition and Its Manifestations
Eosinophilic Colitis involves the migration of eosinophils from the bloodstream into the colon tissue, where they release toxic proteins and chemical mediators. This degranulation causes irritation, swelling, and injury to the colon lining. The specific presentation varies significantly based on a person’s age and the depth of eosinophil infiltration within the colon wall.
In older children and adults, common manifestations include persistent abdominal pain, cramping, and chronic diarrhea that may or may not contain blood. Patients often experience fatigue, poor appetite, and unintentional weight loss due to ongoing inflammation and malabsorption. When infiltration is limited to the mucosal layer, it often results in diarrhea and bleeding. Deeper involvement of the muscular layer can lead to thickening of the bowel wall, and severe mucosal damage may cause protein-losing enteropathy, where proteins leak into the gastrointestinal tract instead of being absorbed.
Identifying the Root Causes
Eosinophilic Colitis mechanisms are strongly linked to the immune system and allergic hypersensitivity. The condition is considered an exaggerated immune response, often involving a reaction to environmental triggers in genetically susceptible individuals. A personal or family history of other allergic or atopic conditions, such as asthma, eczema, or hay fever, increases the risk of developing EC.
In infants and young children, EC is frequently associated with specific food proteins, acting as a non-IgE-mediated food allergy. Cow’s milk protein is a commonly identified trigger, and soy protein also plays a role in some cases. For adults, the immune response is often more complex, sometimes involving T-lymphocyte-mediated hypersensitivity rather than a typical IgE-driven allergic reaction. This suggests the immune system mistakenly targets substances, such as food or environmental antigens, that are normally harmless.
Diagnostic Procedures
A diagnosis of Eosinophilic Colitis cannot be made based on symptoms alone, as they overlap with other inflammatory bowel diseases and infections. The diagnostic process is one of exclusion, requiring doctors to first rule out other potential causes of colonic eosinophilia, such as parasitic infections, drug reactions, or other forms of IBD. The initial workup often includes a complete blood count to check for peripheral eosinophilia, an elevated level of eosinophils circulating in the blood, though this finding is not always present in EC patients.
The conclusive step for diagnosis is a colonoscopy, during which a gastroenterologist examines the large intestine and takes tissue samples (biopsies). A pathologist examines these biopsies under a microscope to count the eosinophils present in the colon lining. Unlike in the esophagus, there is no universal consensus on the exact number of eosinophils per high-power field (HPF) considered diagnostic for EC. Experts typically use a cutoff point that exceeds the normal count for that segment, sometimes suggesting a threshold of greater than 40 eosinophils per HPF in at least two different colonic segments.
Therapeutic Approaches
Treatment for Eosinophilic Colitis focuses primarily on reducing inflammation caused by eosinophils and managing symptoms. Management involves a combination of pharmacological interventions and dietary modifications. Corticosteroids are a frequent first-line treatment due to their powerful anti-inflammatory effects.
Pharmacological Interventions
Systemic corticosteroids, such as prednisone, may be used for moderate or severe cases to quickly bring inflammation under control. For milder disease or to reduce systemic side effects, a localized steroid like Budesonide may be used, which works mainly in the gastrointestinal tract. Anti-allergy medications, including antihistamines and leukotriene receptor antagonists, may also be prescribed as adjunctive therapy to block the chemical pathways involved in the allergic response.
Dietary Management
Dietary management is a cornerstone of treatment, especially in infants and children. This involves identifying and removing specific food triggers through elimination diets. In severe cases, or for young children with multiple food sensitivities, an elemental diet consisting only of amino acids may be necessary to allow the gut to heal completely.