Eosinophilic Gastroenteritis With Perforation Mimicking Intussusception

Abstract

INTRODUCTION Eosinophilic gastroenteritis (EGE) is a rare disorder of unknown origin that is pathologically characterized by marked infiltration of eosinophils in the wall of the gastrointestinal (GI) tract. Eosinophilic gastroenteritis is often classified according to the layer of the bowel wall involved: mucosal, muscular, subserosal, or transmural. Clinical manifestations are related to the site of GI involvement and the layer of bowel wall involved (1). Perforation of the small intestine as a complication of EGE is rare (2–6), especially in children (2). We report an unusual case of perforated EGE in an 8-month-old infant who presented with periodic irritable crying and bilious vomiting whose abdominal sonography revealed a target mass mimicking intussusception. CASE REPORT An 8-month-old boy was brought to our hospital after periodical irritability for 4 days, followed by bilious vomiting. Upper respiratory tract infection with fever, cough, and rhinorrhea with nasal stuffiness were noted 4 days before this admission. He was born at 40 weeks' gestation by elective cesarean section with a birth weight of 3.6 kg. He initially was formula fed, weaned at 5 months with the introduction of baby foods, and his mother practiced no dietary restrictions. He fed well with satisfactory weight gain (9.8 kg, 75th percentile) and normal bowel habits. There was no family or personal history of allergy. Physical examination revealed mild abdominal distention and a palpable abdominal mass in the right lower quadrant. Laboratory tests revealed a hemoglobin concentration of 10.2 g/dL, hematocrit of 31.1%, white blood cell count of 12,700/mm 3 with a normal differential and only 3.4% eosinophils, and the absolute eosinophil count was 210/mm 3 (normal, 50–350/mm 3 ). The serum IgE level was within normal limits (≤100 KU/L) and the Pharmacia CAP system (Pharmacia & Upjohn Diagnostics AB, Uppsala, Sweden) was negative for egg white, milk, peanut, soya bean, shrimp, and wheat allergen. Other normal laboratory values included serum IgA and complement concentrations. Abdominal sonogram demonstrated a discrete mass with dense central echoes and hypoechoic periphery (a “target” pattern) (Fig. 1). Under the impression of intussusception, barium enema reduction was subsequently performed, but persistent obstruction of the retrograde barium flow at the proximal ascending colon was noted. At laparotomy, an inflammatory mass at the ileocecal area with perforation and adhesion to the adjacent intestinal loops and mesentery was found. The mass was resected and an end-to-end ileocolic anastomosis was performed. Histologic examination revealed transmural infiltration of the ileum with inflammatory cells, which were mainly composed of eosinophils (Fig. 2), and abscess formation due to perforation. No features of parasites, vasculitis, or embolism could be detected in the resected specimen. The patient made an uneventful postoperative recovery. He had no further feeding difficulty or irritability episodes, even with cow milk and a normal diet after his first birthday.FIG 1.: Abdominal sonogram shows a right lower quadrant mass with a central echogenic core surrounded by a hypoechoic rim (target sign).FIG 2.: Pathologic examination of the resected mass reveals transmural inflammatory infiltrate (A, hematoxylin and eosin, ×8), which is composed mainly of eosinophils (B, hematoxylin and eosin, ×100).DISCUSSION Eosinophilic gastroenteritis is an uncommon condition pathologically characterized by marked infiltration of eosinophils into the wall of the GI tract, occurring mainly in the stomach and small bowel. The clinical manifestations vary with the anatomic location and predominant layer of the gut wall involved. Depending on the predominant layer involved, it is classified as mucosal, muscular, serosal, or transmural type. When there is transmural infiltration of the small bowel, as in this patient, intermittent subacute obstruction, perforation, and intussusception may occur. However, deep ulceration and subsequent perforation in the small intestine have rarely been reported (2–6). In 1977, Hoefer et al. (2) reported the only other pediatric case. That patient presented with an acute abdomen secondary to distal ileitis with free perforation. To our knowledge, sealed-off perforated EGE manifested as an inflammatory mass in a pediatric patient has not previously been documented. The diagnostic criteria of EGE include the presence of GI symptoms, eosinophilic infiltration of the GI tract, and peripheral eosinophilia. However, as with our patient, absence of peripheral eosinophilia has been reported in 23% to 40% of patients (2,7,8). There was no overall correlation between the peripheral eosinophil counts and the degree of tissue eosinophilic infiltration or epithelial damage (9). Furthermore, neither history of allergy nor high IgE levels is required for the diagnosis (1,10). Kelly (11) emphasized that a pathologist diagnoses this disorder, with clinical correlation from a practitioner. Confirmation of the diagnosis requires histologic evidence of significant eosinophilic infiltration of the GI tract, although not all intestinal eosinophilic infiltrates are due to EGE. In this patient, other possible causes such as parasitic infestation, Crohn disease, celiac diseases, malignancy, or vasculitis syndrome were excluded based on pathologic findings. Additionally, the absence of any abnormal findings outside the digestive tract can rule out the possibility of connective tissue diseases and hypereosinophilic syndrome. Sonographic diagnosis of EGE has shown thickening of all the layers of the bowel wall (12–14), or pseudokidney (or target sign) (15,16). The classic pseudokidney, or target sign, has once been described as a sign of intussusception with a central echogenic core surrounded by a hypoechoic rim. However, a variety of other benign or malignant intestinal diseases including lymphoma, Crohn disease, ischemia, tuberculosis, lymphangiectasia, intramural hematoma, appendicitis, and other inflammatory diseases may also exhibit this target pattern on sonogram (16–19). As illustrated in this case, EGE should also be considered as a rare differential diagnosis of sonographic target lesion because it may occasionally induce bowel obstruction with clinical features mimicking intussusception in pediatric patients. From the therapeutic point of view, EGE can also be classified into protein-sensitive and idiopathic forms. The protein-sensitive form may respond to elimination diets but the idiopathic form will not (20). In the idiopathic form, the triggering factor remains unknown. Other environmental allergens, viral infection most likely in our case, may provoke gastrointestinal tract involvement. Because the cause is unknown, there currently is no satisfactory treatment, although elimination diets have been tried in most cases, primarily in patients with mucosal disease and history of atopy or food intolerance (7). Current evidence is not convincing for successfully treating EGE with diet alone in most patients, so alternative treatments should be considered (21). Treatment with steroids seems most successful (7) but should be cautiously administered, especially in cases with surgical indications. Improvement with ketotifen (22), montelukast (23), or sodium cromoglycate (24) has been reported, but controlled trials are lacking for any therapies (24). Surgery is always indicated for obstruction (25) or perforation of the GI tract (2–6). Complete resection of the affected segment may be curative (5,9,25). Our case shows that perforated EGE may not manifest as a hollow-organ perforation with pneumoperitoneum. Instead, it may present as an inflammatory mass clinically mimicking intussusception. Although in this EGE patient, only a single area in the gut was involved, the possibility that this child will develop further symptoms remains and long-term follow-up is necessary.