Eosinophilic enterocolitis: A rare nosological entity

Eosinophilic enterocolitis is the least common subgroup of the broad spectrum of primary eosinophilic gastrointestinal disorders which can be subdivided into eosinophilic esophagitis, eosinophilic gastritis, eosinophilic enteritis, and eosinophilic colitis [1]. Since the small intestine is not frequently biopsied, there is little evidence related to eosinophilic enteritis [2]. Since 1979, only a few cases of eosinophilic colitis have been reported [2]. Its exact prevalence remains unknown, with a peak of prevalence in newborns and young adults and without any gender preference [2]. In this article, we present the case of eosinophilic enterocolitis in a 45-year-old woman and we discuss in the light of the data of the literature the diagnostic and therapeutic dilemma of this nosological entity.


Introduction
Eosinophilic enterocolitis is the least common subgroup of the broad spectrum of primary eosinophilic gastrointestinal disorders which can be subdivided into eosinophilic esophagitis, eosinophilic gastritis, eosinophilic enteritis, and eosinophilic colitis [1]. Since the small intestine is not frequently biopsied, there is little evidence related to eosinophilic enteritis [2]. Since 1979, only a few cases of eosinophilic colitis have been reported [2]. Its exact prevalence remains unknown, with a peak of prevalence in newborns and young adults and without any gender preference [2]. In this article, we present the case of eosinophilic enterocolitis in a 45-year-old woman and we discuss in the light of the data of the literature the diagnostic and therapeutic dilemma of this nosological entity.
On physical examination, she was non-feverish with normal vital signs. She was malnourished and dehydrated with cleft muscle and fat panicle. The edema of the lower extremities was soft white on the scoop with an absence of protein in the urine strips. Examination of the abdomen revealed abdominal tenderness of the right iliac fossa without defense or contracture and no other associated signs.
Coproparasitological examination of the stool did not isolate pathogens. The serum immunoglobulin E assay was normal at 31 KU / l (N <150KU / l) and HIV serology was negative. The myelogram was without abnormalities.
At this stage an infectious attack was initially suspected without being able to rule out an infl ammatory or tumor attack.
Due to concern for parasitic infection, the patient was placed on intravenous metronidazole. The abdominal ultrasound did not show any abnormalities apart from two small ovarian cysts.

Discussion
Eosinophilic enterocolitis is a disease entity linked to abnormal infi ltration of the intestinal mucosa by polynuclear eosinophils. It is a rare entity on the spectrum of gastrointestinal eosinophilic disorders [3]. Gastroenteritis and eosinophilic colitis represent an estimated incidence of 22 to 28 cases / 100,000 in the United States [4].
The pathogenesis of eosinophilic gastrointestinal disorders is not well understood. They probably result from a complex interaction between environment, genetics and immunological factors [5]. Several epidemiological studies suggest an allergic component, in particular food allergies, which elicits a Th2type immune response leading to the production of cytokines, such as interleukins, IL-4, IL-5, IL-13 and eotaxins-3. This results in intestinal eosinophilia, which further causes local infl ammation by releasing toxic cationic proteins [6]. Even less is known about the etiology of primary eosinophilic colitis. It is associated with food allergies and atopy in several cases described [1]. It can probably be both an IgE and non-IgE mediated disease [7].    Klein, et al. [8] proposed a classifi cation system based on the depth of parietal infi ltration. Mucosal infi ltration is the most common type and is characterized by eosinophilic infi ltration of the mucosa and sub-mucous membrane. Muscle type is characterized by muscle involvement. The serous type affects all layers and is considered the rarest type [9]. The mucosal type is associated with persistent chronic symptoms and can lead to enteropathy with loss of protein [10].
The diagnosis of eosinophilic enterocolitis is an exclusion diagnosis that requires a high level of suspicion. It is based on the association of non-specifi c gastrointestinal symptoms, the demonstration of an eosinophilic infi ltration on the biopsies, and the exclusion of secondary causes of eosinophilic infi ltration such as parasitoses, drugs, chronic infl ammatory bowel disease, malignant causes, autoimmune damage and eosinophilic syndrome [7,11]. There are no standardized histological criteria to make the diagnosis [2]. Peripheral eosinophilia can be observed, but may be absent in 20% of patients. Sectional imaging results are non-specifi c and may show thickening of the intestinal wall and ascites in some cases [12].
The treatment of eosinophilic enterocolitis remains a challenge in the absence of specifi c recommendations as there are no controlled trials to date on a specifi c treatment [9]. So far, the treatment of eosinophilic enterocolitis has been empirical and based on the severity of clinical manifestations, as well as the experience of clinicians. Patients with mild disease can be treated symptomatically, while more symptomatic patients and those with signs of malabsorption need more aggressive treatment [13].
A high proportion of cases of eosinophilic gastroenteritis are associated with food allergy. Therefore, diet therapy may improve symptoms [12]. It involves a "six-food elimination diet," avoiding milk, soy, eggs, wheat, peanuts / tree nuts, and shellfi sh / fi sh. The main limitation of diet therapy is patient compliance.
Corticosteroids are the optimal therapy for the induction of remission. Oral prednisone is the most common therapy, with an initial dose of 0.5-1 mg / kg and decreased over a period of 6-8 weeks. Relapses can occur and require low maintenance doses (1 to 10 mg / day) of prednisolone [14] or the substitution of prednisolone by budesonide which has a better safety profi le [15,16].
Other therapies targeting immune modulation have been described in reports, and small case series, will likely be useful in treating recurrent or refractory symptoms. They include mast cell inhibitors such as cromolyn, ketotifen, leukotriene receptor antagonists, anti-IL-5 antibodies, omalizumab, and anti IgE monoclonal antibodies [13].

Conclusion
Our clinical case highlights a rare entity that is often underdiagnosed. Further studies are needed to better defi ne diagnostic criteria for this entity. Randomized controlled trials are also needed to establish a standardized treatment approach.