Discussion
Eosinophilic gastroenteritis (EG) is a chronic inflammatory disorder that is characterized by variable degrees of infiltration of eosinophils within the gastrointestinal tract. EG can occur at any age, and was first described by Kaijser in 1937 [8]. The true incidence of EG remains unclear due to its rare nature, and most of the literature is mainly case reports. Although no accurate epidemiologic data are available, the incidence of EG is estimated to be approximately 1-30/100,000 [3,4], and the prevalence seems to have been increasing in the past two decades [9]. Eosinophils are normally present in the lamina propria, except the esophagus, and the number of eosinophils along the GI tract varies, with the highest concentrations found in the cecum and appendix [10]. Eosinophils are involved in the mucosal immune system of the GI tract and play a role in host defense in healthy individuals [11]. The number of eosinophils increases during the pathogenesis of numerous inflammatory processes, including parasitic infections and allergic diseases. Then, the activated eosinophils produce and release highly bioactive inflammatory mediators, which may lead to a series of problems in the GI tract [12,13]. However, the exact mechanism of the pathogenesis of EG is still unclear.
Although the etiology and pathogenesis of EG remain unclear, there are studies suggesting that approximately 45–63% of patients diagnosed with EG had a history of allergies, such as asthma, rhinitis, drug or food allergies; eczema; and parasitic infections [14,15], while others have found an association with other autoimmune conditions, such as HIV infection [16], influenza A virus infection [17], ulcerative colitis, and systemic lupus erythematosus [14]. The clinical manifestations of EG are not specific. The manifestations depend on the extent and depth of eosinophilic infiltration into the gastrointestinal tract wall. Three clinical forms are classified, mucosa, muscularis, and serosal, which are based on the Klein classification from 1970 [5]. The form involving the mucosal layer is the most common type, which can manifest as abdominal pain, hematochezia, diarrhea, hypoproteinemia and weight loss. Patients with EG that involves the muscularis can present with intestinal obstruction and even perforation. When the serosal layer is affected, ascites are the main manifestation. Full layer involvement is rare. Endoscopic findings may vary from nonspecific to mucosal erythema and ulceration [18]. Therefore, EG is easily misdiagnosed due to its various clinical and endoscopic manifestations.
In our case, we diagnosed the patient with eosinophilic gastroenteritis, and the full layer of the gastrointestinal wall was involved, mainly based on the following clinical evidence: First, signs of gastrointestinal whole wall involvement, such as diarrhea with blood and mucus, hypoproteinemia, abdominal pain, and abdominal distention, were observed. Second, endoscopic tissue biopsy revealed marked eosinophilic infiltration in the gastric antrum and sigmoid colon mucosa layer; eosinophils in peripheral blood and ascites increased significantly. Abdominal CT showed signs of thickened intestinal wall and ascites. Finally, the corresponding examination was improved to exclude tuberculosis peritonitis, IBD, parasitic infection, malignant tumor, intestinal Behcet’s disease, lymphoma, and eosinophilia. Unfortunately, deep biopsies of the gastrointestinal tract were not available for additional evidence.
Corticosteroid therapy is the mainstay of EG treatment in both adults and children. Other therapies include dietary therapy, leukotriene inhibitors, mast cell stabilizers, interleukin-5 inhibitors, ketotifen, and biological agents [13,19]. We recommended methylprednisolone therapy to the patient, and the above symptoms were significantly relieved and eosinophils gradually decreased to normal. There was no recurrence after 6 months of follow-up.
Due to the lack of clinical experience, and little attention has been paid to the eosinophilic infiltration in the process of pathological diagnosis, doctors in primary hospitals misdiagnosed as cholelithiasis, and even cholecystectomy has been done. In conclusion, EG is a rare gastrointestinal disease with atypical clinical manifestations that are easily misdiagnosed. Timely and correct diagnosis depends on the clinician’s understanding of the disease. Besides, more attention from the pathologists should be paid to the eosinophilic infiltration in the process of pathologic diagnosis. For patients with increased eosinophils in peripheral blood accompanied by gastrointestinal symptoms, EG should be considered. However, eosinophils in peripheral blood may not increase in some patients, which means further endoscopic multisite biopsy to determine whether eosinophils are infiltrating is the key to diagnosis.