Overview 

Eosinophilic gastroenteritis (EGE) is a rare condition that belongs to a group of disorders known as eosinophilic gastrointestinal diseases (EGIDs). It happens when a type of white blood cell called an eosinophil builds up abnormally in the stomach, small intestine, or large intestine.¹ Other known problems, such as parasite infections, reaction to medications, or conditions like inflammatory bowel disease, do not cause the buildup of eosinophils. Consequently, the symptoms of EGE can vary widely. Some people may experience ongoing abdominal pain and diarrhoea, while others might develop more serious issues such as blocked intestines or a large build-up of fluid in the abdomen (ascites).² The exact symptoms often depend on which layer of the gut wall is affected. One of the challenges with EGE is that its symptoms are very general and can look like many other digestive problems. Even during an endoscopy (a camera test of the digestive tract), the gut may sometimes appear completely normal. This means that doctors need to rely on a combination of approaches, keeping a strong clinical suspicion, performing targeted endoscopies, taking multiple tissue biopsies, and using imaging tests, to confirm the diagnosis and plan treatment.

Disease patterns and why imaging and endoscopy matter

Eosinophillic gastroenteritis (EGE) is usually grouped into three main types, depending on which layer of the intestinal wall is most affected:³

• Mucosal disease - the most common type. It affects the inner lining of the intestine and can lead to problems like poor absorption of nutrients (malabsorption), diarrhoea, bleeding, and loss of protein into the gut (protein-losing enteropathy)
• Muscular disease - this involves the thick muscle layer of the intestine, which can cause the bowel wall to become abnormally thick and sometimes lead to blockages
• Serosal disease - the rarest form, affecting the outer lining of the intestine. It often causes a build-up of fluid in the abdomen (eosinophilic ascites) and can produce more dramatic, whole-body symptoms

Diagnosing EGE can be tricky. Mucosal disease is usually detectable through biopsies taken during an endoscopy, since it involves the surface lining. However, muscular and serosal types often spare this surface layer, meaning biopsies can appear normal. In these cases, imaging tests such as an ultrasound, CT, or MRI are especially important to help doctors see what’s happening deeper in the gut wall.

Endoscopic findings: Expectations and pitfalls 

Key point: Normal mucosa does not rule out EGE

A very important fact for clinicians is that a normal-looking gut lining during endoscopy does not exclude eosinophillic gastroenteritis (EGE). Large studies and reviews have shown that in 60% to more than 80% of patients, the bowel appears normal in endoscopy.⁴ This means that relying only on the visual appearance of the gut can lead to missed diagnoses. Instead, doctors should use a combination of symptom-based targeting, imaging guidance, and empirical (broad) biopsies to increase the chance of detection. 

Typical endoscopic findings (when abnormalities are seen)

Although no single feature is unique or diagnostic (“pathognomonic”), certain patterns have been described depending on the site:

• Stomach (Eosinophilic Gastritis)

Endoscopy may reveal redness (erythema), swelling (edema), erosions or ulcers, nodularity, and sometimes a cobblestone-like or granular surface. Some reports describe white spots or unusual nodularity, but these findings are inconsistent and can overlap with other gastric conditions⁵

• Small Bowel (Eosinophilic Enteritis)

Using capsule endoscopy or enteroscopy, doctors may see villous blunting or atrophy, mucosal redness, erosions, circumferential ulcers, and strictures.⁶ Narrowed areas (stenosis) can even trap the capsule during testing. Because of these findings, particularly circumferential ulcers, EGE of the small bowel is sometimes mistaken for Crohn’s disease

• Colon (Eosinophilic Colitis)

Endoscopic features are usually non-specific to Eisinophilic Gastroenteritis: mucosal redness, swelling, erosions, and sometimes polyps or nodular changes.⁷ These appearances are visually indistinguishable from other causes of colitis, which reinforces the need for biopsies 

Practical biopsy tips for endoscopists 

• Always take multiple biopsies, even from the gut areas that look normal. Eosinophil infiltration can be patchy, and sampling only abnormal-looking spots risks underdiagnosis⁸
• In suspected muscular or serosal disease, where the mucosa often looks normal, cross-sectional imaging (ultrasound, CT, MRI) becomes critical. If suspicion remains high, a deep or full-thickness surgical biopsy may be needed for a definite diagnosis 
• Work closely with pathologists. Clearly indicate suspected EGID on the pathology request, so that eosinophil counts, distribution patterns, and evidence of eosinophil degranulation are reported, rather than just routine tissue descriptions

Imaging findings in eosinophilic gastroenteritis: Modality-specific roles 

Because eosinophilic gastroenteritis (EGE) often affects deeper layers of the bowel wall, imaging is essential for diagnosis and treatment, especially when endoscopic biopsies are normal. Each modality offers distinct strengths:

Intestinal Ultrasound (IUS) / Abdominal ultrasound 

• Findings: Bowel wall thickening with preservation of normal wall layering (stratification), enlarged mesenteric lymph nodes, and free fluid in cases of serosal involvement⁹ 
• Strengths: Inexpensive, widely available, radiation-free, and repeatable, making it excellent for follow-up
• Role in EGE: Particularly valuable in mucosal and serosal disease, where superficial mucosal biopsies may miss pathology 
• Evidence: Recent care series and reviews emphasise ultrasound as a frontline tool in suspected EGE

CT / CT enterography (CTE)

• Findings: Segmental or diffuse bowel wall thickening, mucosal hyperenhancement, and a layered "stratified" appearance of the wall. It may also reveal mesenteric fat standing and ascites (especially in serosal disease)¹⁰
• Complications: Concentric thickening, narrowing, and signs of obstruction may be seen in muscular disease. CT is crucial when evaluating for serious complications such as obstruction, perforation, or intussusception
• Key Sign: A recent 2024 review described the “piano-key sign”, where alternating layers of enhancement suggest EGE¹⁰
• Evidence: Widely reported in case series and imaging reviews

MRI / MR enterography 

• Findings: Similar to CT, demonstrating mural thickening, enhancement, and edema, while also assessing strictures and extra-intestinal features¹¹
• Strengths: No ionising radiation, making it preferable for younger patients and those requiring serial imaging
• Role in EGE: Particularly useful in chronic and relapsing cases to monitor mural inflammation and progression
• Evidence: Increasingly favoured in longitudinal follow-up

Barium studies and Capsule endoscopy 

• Barium Studies: Historically showed segmental narrowing, ulcerations, and strictures, but their role has largely been replaced by cross-sectional imaging and endoscopy¹²
• Capsule Endoscopy: Can detect small bowel ulcers, erosions, and villous atrophy.¹³ However, a major limitation is the risk of capsule retention in patients with strictures, which has been reported in EGE. A patency capsule is recommended if obstruction is suspected 

How imaging and endoscopy complement each other in practice 

Endoscopy and imaging play complementary roles in diagnosing eosinophilic gastroenteritis (EGE):

• When endoscopy shows visible mucosal lesions (erythema, erosions, nodularity, ulcers), taking biopsies from these areas usually provides a diagnosis, especially in the mucosal type of EGE
• When endoscopy results looks normal, EGE cannot be excluded. In fact, up to 60–80% of patients may have a normal-appearing mucosa despite disease. In these cases, cross-sectional imaging becomes crucial, particularly for identifying muscular or serosal involvement

Imaging findings such as transmural bowel wall thickening, ascites, or strictures often point to deeper disease. If mucosal biopsies are non-diagnostic but clinical suspicion remains high, the next steps may include: 

• Deeper biopsies (endoscopic ultrasound-guided, laparoscopic, or surgical full-thickness sampling)
• Empirical treatment, in carefully selected cases, after ruling out other secondary causes of esoinophiilia

Together, endoscopy and imaging provide a layered diagnostic approach: endoscopy excels at detecting surface disease, while imaging is decisive for deeper wall involvement that mucosal biopsies may miss.

Differential diagnosis and common pitfalls 

Eosinophilic gastroenteritis (EGE) is often difficult to distinguish from other gastrointestinal diseases because of its overlapping clinical, endoscopic, and radiologic features.

Conditions that mimic EGE include:¹⁴

• Crohn’s disease - similar findings of ulcers, strictures, and transmural inflammation
• Infectious enteritis - bacterial, viral, or parasitic causes may produce diarrhea, mucosal inflammation, or eosinophil-rich infiltrates
• Ischemic bowel disease - can present with abdominal pain, wall thickening, and ulcerations
• Gastrointestinal lymphoma - mass-like thickening or strictures can resemble muscular EGE
• Hypereosinophilic syndromes - systemic disorders with high eosinophil counts affecting multiple organs
• Drug-induced reactions - certain medications can trigger gastrointestinal eosinophilia

Key differentiating clues:¹⁵

• Peripheral eosinophilia: Present in many, but not all, cases of EGE
• Histology: The pattern and distribution of mucosal eosinophils, along with evidence of degranulation, help separate EGE from other causes
• Radiologic findings: Diffuse, stratified wall thickening with ascites is more suggestive of EGE in the right clinical setting
• Response to therapy: A favourable and rapid response to corticosteroids supports the diagnosis of EGE

Critical step: Always rule out secondary causes of eosinophilia, particularly parasitic infection and drug-induced changes, before labelling a case as primary EGE.

Practical takeaways for clinicians 

• Maintain clinical suspicion: symptoms are nonspecific; consider EGE in chronic abdominal pain, refractory diarrhoea, protein-losing enteropathy, obstructive symptoms, or eosinophilic ascites
• Don’t be reassured by a normal endoscopic appearance; take multiple biopsies from symptomatic segments and consider random biopsies of normal mucosa when suspicion is high
• Use ultrasound and CT/MR enterography early when muscular/serosal disease is suspected or when endoscopy is non-diagnostic
• Coordinate with pathology and consider a deeper (full-thickness) biopsy if imaging suggests transmural disease
• Interpret imaging/endoscopy in the clinical context and exclude secondary causes before committing to immunosuppressive therapy

FAQs

Can EGE be diagnosed with a single endoscopic biopsy?

No. Eosinophil infiltration is often patchy. Multiple biopsies from different segments, and sometimes biopsies of endoscopically normal mucosa, are commonly required. In muscular/serosal disease, mucosal biopsies may be normal, and deeper tissue sampling or imaging is necessary.

Which imaging study is best to start with?

Abdominal/intestinal ultrasound is an excellent, low-cost first step (especially for muscular/serosal suspicion), with CT enterography or MR enteropgraphy reserved for more detailed assessment for complications. CT is preferred for acute complications and detailed luminal evaluation.

Can imaging be used to monitor treatment response?

Yes. Ultrasound and cross-sectional imaging can track changes to bowel wall thickness, enhancement, and ascites, and are useful tools for monitoring patients, particularly those with muscular or serosal disease.

Summary

Eosinophilic gastroenteritis is a biologically and clinically heterogeneous disease in which endoscopy, histology, and imaging each play complementary roles. While mucosal disease is often diagnosed with multiple targeted biopsies, muscular and serosal forms frequently require cross-sectional imaging (ultrasound, CT, MR) to detect transmural thickening, ascites, and strictures. Importantly, a normal endoscopic appearance does not exclude EGE; clinicians must combine suspicion, coordinated biopsies, and imaging to avoid missed diagnoses and provide effective treatment.