Quantitative Analysis of Distribution of the Gastrointestinal Tract Eosinophils in Childhood Functional Abdominal Pain Disorders

BACKGROUND/AIMS: Although functional abdominal pain disorders (FAPDs) are common in children, the accurate pathogenesis of FAPDs is not known yet. Micro-inflammation, particularly tissue eosinophilia of gastrointestinal (GI) tract, has been suggested as the pathophysiology observed in several GI disorders. We aimed to evaluate eosinophilic infiltration throughout the entire GI tract in children with FAPDs, compared to those with inflammatory bowel diseases (IBD) and to normal reference values. METHODS: We included 56 children with FAPDs, 52 children with Crohn’s disease, and 23 children with ulcerative colitis. All subjects underwent esophagogastroduodenoscopic and colonoscopic examination with biopsies. Tissue eosinophil counts were assessed in 10 regions throughout the GI tract. RESULTS: Eosinophil counts of the gastric antrum, duodenum, terminal ileum, cecum, and ascending colon were significantly higher in children with FAPDs compared to normal reference values. Eosinophil counts of the stomach and the entire colon were observed to be significantly higher in children with IBD than in those with FAPDs. Even after selecting macroscopically uninvolved GI segments on endoscopy in children with IBD, eosinophil counts of the gastric body, cecum, descending colon, sigmoid colon, and the rectum were also significantly higher in children with IBD than those with FAPDs. CONCLUSIONS: Significantly high eosinophil counts of the stomach and colon were observed in the order of IBD, followed by FAPDs, and normal controls, regardless of endoscopically detected macroscopic IBD lesions in children. This suggests some contribution of GI tract eosinophils in the intrinsic pathogenesis of FAPDs in children.