Eosinophilic Gastroenteritis Workup

The evaluation starts with a comprehensive history and physical examination. The diagnosis of eosinophilic gastrointestinal conditions, including eosinophilic gastroenteritis, is one of exclusion and requires the presence of gastrointestinal symptoms, the presence of gastrointestinal eosinophilia on biopsy specimens, and the exclusion of other known causes of tissue eosinophilia. ^{[1, 11]}

General workup includes a complete blood cell (CBC) count and differential. Peripheral blood eosinophilia is found in 20-80% of cases. The average count is 2000 eosinophils (eos)/µL in patients with mucosal layer involvement, 1000 eos/µL in patients with muscular layer involvement, and 8000 eos/µL in patients with serosal involvement.

Mean corpuscular volume measurements may reveal iron-deficiency anemia, and serum albumin levels may be low, especially in patients with mucosal layer involvement.

Also note the following:

• Although usually unnecessary, fecal protein loss can be measured by measuring alpha1-antitrypsin in a 24-hour feces collection. This test is used to identify the inability to digest and absorb proteins in the GI tract. The normal value is 0-54 mg/dL. Patients with eosinophilic gastroenteritis have elevated alpha1-antitrypsin in their feces. Obtain a stool sample (minimum 2-g portion), and keep it refrigerated.

• Protein loss also can result in a low level of quantitative immunoglobulins.

• The erythrocyte sedimentation rate (ESR) and serum IgE level can be elevated.

• Obtain three separate stool specimens to rule out parasitic infection. Perform a wet mount or stain smear.

• Mild-to-moderate steatorrhea is present in approximately 30% of patients. This can be measured by qualitative and quantitative stool tests.

• Skin prick tests to inhalant allergens and food help identify sensitization to specific allergens.

• The diagnosis of eosinophilic gastroenteritis depends on microscopic evaluations of endoscopic biopsy specimens. Examine specimens from each intestinal segment with particular attention to the following: (1) eosinophil quantification; (2) the location of eosinophils especially if present in the intraepithelial, superficial mucosal, and intestinal crypts; (3) the presence of extracellular eosinophilic granules; (4) associated pathologic abnormalities; and (5) the absence of other primary disorders (ie, vasculitis).

Radiography

Radiographically, eosinophilic gastroenteritis does not have a pathognomic appearance. Radiographic changes are variable, nonspecific, and/or absent in at least 40% of patients. Note the following:

• Gastric folds can be enlarged, with or without nodular filling defects.

• Valvular conniventes may be thickened and flattened. Strictures, ulceration, or polypoid lesions may occur.

• In eosinophilic gastroenteritis involving the muscle layer, localized involvement of the antrum and pylorus may occur, causing narrowing of the distal antrum and gastric retention. The small intestine also may be dilated, with an increase in the thickness of the folds. Prominent mucosal folds also may be observed in the colon.

• Rarely, diffuse esophageal narrowing or achalasia-like motor abnormalities may occur.

Ultrasonography and computed tomography (CT) scanning

Abdominal ultrasonographic images and CT scans may show thickened intestinal walls and, sometimes, localized lymphadenopathy. ^[12] Ascitic fluid usually is detected in patients with serosal layer involvement.

Endoscopy and biopsy

Note the following:

• When eosinophilic gastroenteritis is suspected, obtain biopsy samples from the gastric antrum and duodenum. ^{[13, 14]} It is not recommended that biopsy samples be placed in Bouin preservative, as this can cause difficulty in identifying eosinophils. ^[14]

• Because of possible sampling error, when performing endoscopy, obtain at least 6 biopsy specimens from normal and abnormal areas of the bowel.

• Grossly prominent mucosal folds, hyperemia, ulceration, or nodularity may be apparent.

• In patients with esophageal or colonic symptoms, obtain additional biopsy specimens from the relevant sites to aid in the diagnosis. Gastroesophageal reflux can cause tissue eosinophilia in the distal esophagus. See the images below.

  Biopsy specimen of eosinophilic gastroenteritis.

  View Media Gallery

  Biopsy specimen of eosinophilic gastroenteritis.

  View Media Gallery

Paracentesis

Patients with serosal disease present with ascites. Abdominal paracentesis demonstrates a sterile fluid with a high eosinophil count. Pleural effusion also may be present. Laparoscopy may show hyperemia and/or nodularity of the GI wall.

Laparotomy

Exploratory laparotomy may be indicated, especially in patients with serosal eosinophilic gastroenteritis.

Histopathology usually demonstrates increased numbers of eosinophils (often >50 eos per high-power field) in the lamina propria. Large numbers of eosinophils often are present in the muscularis and serosal layers. The localized eosinophilic infiltrates may cause crypt hyperplasia, epithelial cell necrosis, and villous atrophy. The gross appearance of eosinophilic gastroenteritis upon endoscopy shows erythematous, friable, nodular, and, often, ulcerated mucosa. Diffuse enteritis with complete loss of villi, submucosal edema, infiltration of the GI wall, and fibrosis may be apparent. Mast cell infiltrates and hyperplastic mesenteric lymph nodes infiltrated with eosinophils may be present. Because of errors in sampling or to mucosal sparing, 10% of mucosal biopsies are not helpful to establish a diagnosis.

Histologic analysis of the small intestine reveals increased deposition of extracellular major basic proteins (MBPs) and eosinophilic cationic proteins (ECPs).