Case Report : Importance of dietary modification in successful management of eosinophilic gastroenteritis [ version 1 ; peer review : awaiting peer review ]

Eosinophilic gastroenteritis (EGE) is an extremely rare Introduction: inflammatory disorder with an estimated prevalence of 22-28/100 000. We herein, present a case of EGE in an elderly patient which was successfully managed with dietary restriction. A 70-year-old male with a history of gastroesophageal reflux Case report: disorder (GERD), atopic dermatitis and asthma presented with 2 weeks history of foul-smelling non-bloody diarrhea associated with nausea, vomiting and weight loss. Physical examination was significant for dry oral mucosa and loss of skin turgor. Lab findings were significant for a hemoglobin of 13.2 g/dl, hematocrit of 38.5%, mean corpuscular volume of 86.3%, white blood cell count of 24,200/mm3, albumin of 2.2 g/L, stool fat of 70g, stool osmolar gap of 115, C-reactive protein 1.47. Erythrocyte sedimentation rate, HIV test were unremarkable. Infectious stool work-up was negative. Computed tomography of the abdomen was unremarkable. The mucosa appeared mildly inflamed on upper endoscopy and colonoscopy, and biopsies showed eosinophilic infiltration of the mucosal and muscular layers. A diagnosis of eosinophilic gastroenteritis was made after other causes such as parasitic infection, drug use and malignancy were ruled out. The patient was counseled on a six-food elimination diet which successfully resolved his diarrhea. The patient did not have any relapses with dietary modification on follow-up. The recurrence rate of EGE is 50%. Steroids improve Discussion: symptoms in 90% of cases but the recurrence rates are high. The type, dose and duration of steroid therapy is unclear. Sodium cromoglicate, ketotifen, and Montelukast are other proposed treatments, the results being inconclusive. Bowel resection is performed in intestinal obstruction, but medical therapy is needed as recurrence in other segments in common. Dietary modification, a therapy with no side-effects should be the first line of treatment as it can result in resolution sparing the patient of steroid induced side effects.


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Introduction
Eosinophilic gastroenteritis (EGE) is an extremely rare inflammatory disorder with an estimated prevalence of 22-28/100 000. We herein, present a case of EGE in an elderly patient which was successfully managed with dietary restriction. We would like to stress that food allergy is the main culprit in certain cases of EGE and dietary modification should always be the first step in the management of these cases 1 .

Case presentation
A 70-year-old male with a history of gastroesophageal reflux disorder (GERD), atopic dermatitis and asthma presented in August 2018 with 2 weeks history of foul-smelling non-bloody diarrhea associated with nausea, vomiting and weight loss. He did not have a family history of colonic disorders. He denied alcohol use, smoking or use of any other illicit drugs. Physical examination was significant for dry oral mucosa and loss of skin turgor.

Investigations
Lab findings were significant for a hemoglobin of 13.2 g/dl, hematocrit of 38.5%, mean corpuscular volume of 86.3%, white blood cell count of 24,200/mm3, albumin of 2.2 g/L, stool fat of 70g, stool osmolar gap of 115, C-reactive protein 1.47. Erythrocyte sedimentation rate, HIV test were unremarkable. Infectious stool work-up was negative. Computed tomography of the abdomen was unremarkable. The mucosa appeared mildly inflamed on upper endoscopy and colonoscopy, and biopsies showed eosinophilic infiltration of the mucosal and muscular layers. A diagnosis of eosinophilic gastroenteritis was made after other causes such as parasitic infection, drug use and malignancy were ruled out.

Treatment
The patient was suggested a six-food elimination diet which included the elimination of soy, wheat, egg, milk, peanuts, and fish/shellfish and it successfully resolved his diarrhea.

Outcome and follow up
The patient was followed up in the outpatient GI clinic annually and did not have any relapses after dietary modification.

Strengths, Limitations and Take Away Lessons
Simple interventions like dietary changes can prevent recurrences and resolve symptoms in eosinophilic gastroenteritis. Although compliance to dietary changes can be challenging it is nonetheless an intervention without any side effects. The evidence for using steroids, type and duration of steroid therapy is not substantial to indicate its benefits. Use of biological agents in the treatment of EGE is still underway and hence the first line of intervention for the treatment of EGE should start with dietary modification.

Discussion
EGE most commonly affects males in the third decade of life and those with a history of eczema, asthma, allergic rhinitis. The prevalence of EGE is underestimated as it is under diagnosed given the rarity of the condition especially when it presents outside of the age spectrum like in our patient. The pathogenesis of EGE remains unclear and it is hypothesized to be a hypersensitive response to certain allergens. One proposed theory is that infectious and geographical factors interact with certain genetic variants causing esophagic dysbiosis which leads to Th2 cell immune response. Dysregulation of several genes termed EOE transcriptome is also shown to play a role 2,3 .
Laboratory findings seen in EGE include peripheral eosinophilia, elevated serum IgE levels, increased stool fat excretion, prolonged prothrombin time, hypoalbuminemia, anemia from intestinal malabsorption. Imaging can show thickening or nodularity of the antrum and thickened or saw tooth mucosa in the small bowel and when the muscular layer is involved irregular narrowing especially in the distal antrum and proximal small bowel can also be seen. EGE is a diagnosis of exclusion and other causes of hyperreactivity and eosinophilia should be considered such as parasitic infections, vasculitis disorders, reaction to drugs like enalapril, interferons, non-steroidal antiinflammatory drugs (NSAIDs), Helicobacter pylori infection 4 . The diagnosis of EGE is established when the biopsy shows more than expected numbers of eosinophils and all the other causes are ruled out.
Klein et al., classified EGE based on the depth of eosinophilic infiltration. Mucosal disease presents with abdominal pain, nausea/vomiting, diarrhea and the patients develop protein losing enteropathy, malabsorption and failure to thrive. Muscular involvement causes wall thickening and impaired motility which may lead to intestinal obstruction. Serosal disease presents as either isolated ascites or ascites in addition to the symptoms of serosal and muscular disease 5 .
The recurrence rate of EGE is 50% and a dietary trial could be a long-term solution like in our patient. A six-food elimination diet (soy, wheat, egg, milk, peanut/tree nuts, and fish/shellfish) or an elemental diet is recommended. Steroids improve symptoms in 90% of cases but the recurrence rates are high. The type, dose and duration of steroid therapy is unclear. The most commonly used regimen is prednisolone at 20 to 40 mg/day, for 6 to 8 weeks including the tapering although most patients need a longer course due to relapses. Sodium cromoglicate, ketotifen, and Montelukast are other proposed treatments, the results being inconclusive. Bowel resection is performed in intestinal obstruction, but medical therapy is needed as recurrence in other segments is common 6 .
The use of biologics in the treatment of refractory EGE in being studied and could lead to new longer lasting results. Interleukin 5, an eosinophilic growth factor, is shown to play an important role in the pathogenesis of EGE. A few clinical trials assessing the use of anti-interleukin 5 in the form of humanized antibodies have shown improvement in endoscopic appearance, reduced clinical symptoms and improved quality of life while a few clinical trials showed no statistical difference in disease progression with this treatment. Trials to understand if eosinophils are key to the development and progression of eosinophilic esophagitis are underway 8

Conclusion
The clinical guidelines for the diagnosis of EGE is sparse and the treatment offered is low-evidence based. Dietary modification, a therapy with no side-effects should be the first line of treatment and can result in resolution sparing the patient of steroid induced side effects.

Consent
Written informed consent for publication of their clinical details was obtained from the patient.