Elsevier

Human Pathology

Volume 54, August 2016, Pages 55-63
Human Pathology

Original contribution
Histologic analysis of eosinophils and mast cells of the gastrointestinal tract in healthy Canadian children

https://doi.org/10.1016/j.humpath.2016.03.004Get rights and content

Summary

Many gastrointestinal (GI) disorders, including GI eosinophilia and inflammatory bowel disease, can be characterized by increased mucosal eosinophils (EOs) or mast cells (MCs). Normal mucosal cellular counts along the GI tract in healthy children have not been established for a Canadian pediatric population. To establish a benchmark reference, we quantified EO and MC from 356 mucosal biopsies of the GI tract obtained during upper and lower endoscopic biopsies of 38 pediatric patients in eastern Ontario. Mean total counts of EO varied for the 11 tissues we examined, from a low of 7.6 ± 6.5/high-power field (HPF) (× 40 [× 400, 0.55mm2]) in the body of the stomach to a high of 50.3 ± 17.4/HPF in the cecum. The lower GI tract (ileum, cecum, colon, sigmoid, and rectum) generally had higher total EO counts than the upper GI tract (antrum and body of stomach, duodenum, and duodenal cap) (combined average of 32.1 ± 20.6 versus 19.3 ± 15.8, respectively). Similarly, the number of mucosal MC was different in the various regions of the GI tract ranging from 0.04 ± 0.2/HPF in the duodenal cap to 0.9 ± 2.6/HPF in the ileum. Total counts for EO and MC in the lamina propria were not significantly different between sexes when adjusted for multiple testing. EO polarity was absent in many cases, irrespective of the GI region. These numeration and localization of EO and MC will provide normative data for upper and lower endoscopic GI biopsies in the pediatric population of Eastern Ontario.

Introduction

Eosinophils (EOs) are normally observed in the mucosa of respiratory [1], lower genitourinary, and gastrointestinal (GI) tract locations, with the exception of the normal esophagus, which has no EO localization [2]. The precise function of EO in the GI tract is not fully understood, but it is known that they have a role in the mucosal immune response [3]. The number of intramucosal EO is known to be widely variable among individuals depending on age [4], exposure to food allergens, and exposure to infectious agents [5]. Aeroallergens can also induce GI mucosal eosinophilia [6]. Mast cells (MCs) are thought to be prototypes of innate immune cells, and their activation has been implicated in many types of neuroinflammatory responses and related disturbances of gut motility [7]. Quantification of colorectal EO and MC in healthy pediatric populations in 2 studies from the United States [8], [9] established that EO counts also vary by geographic location of residence. To the best of our knowledge, there are no studies that have quantified and qualified EO and MC from upper and lower GI tract endoscopic biopsies in a Canadian pediatric population.

The diagnosis of eosinophilic mucosal diseases is largely based on numeration of EO in GI mucosal biopsies and, to a lesser extent, their distribution. Without reference standards, this renders the diagnosis of abnormal GI eosinophilia subjective. Establishing normal values and distribution of EO and MC in a pediatric population in central Canadian geographic location is of importance and the focus of this study.

Section snippets

Study design

This study was approved by the Children's Hospital of Eastern Ontario (CHEO) Ethics Board. Pathology reports and medical records of patients who underwent a GI biopsy at CHEO between April 2013 and April 2014 were collected and reviewed. Data were extracted on patient demographics (eg, sex, age) and clinical information (eg, indication for biopsy, diagnosis). Study inclusion criteria were as follows: age younger than 18 years, normal macroscopic visualization of the mucosa during endoscopy, no

Patient characteristics

A total of 653 GI biopsies were performed at CHEO between April 2013 and April 2014; however, only 356 biopsies from 38 patients (22 females and 16 males) from endoscopically normal mucosa in healthy patients were studied that met the inclusion criteria. The median age of included patients was 13 (range, 1-17) (Table 1). Indications for endoscopic biopsy included abdominal pain (n = 12; 31.6%), rectal bleeding (n = 9; 23.7%), chronic diarrhea (n = 3; 7.9%), vomiting (n = 1; 2.6%), recurrent perianal

Discussion

In our study, we found EO counts ranged widely between the different tissues and locations (lamina propria, surface epithelium, crypts/glandular epithelium) throughout the GI tract, with gradual increases from the stomach to the cecum and then gradual decreases from the cecum to the rectum. MCs were present throughout the entire GI tract in the lamina propria of biopsy tissues, and the majority of examined biopsies did not show a high degree of preserved polarity.

Regional variation in EO along

Study impact/conclusion

This study is the first of its kind in Ontario and Canada to set the baseline count and distribution for normal EO and MC in the GI tract in the pediatric population of eastern Ontario. We can conclude that, at baseline, EO and MC are located throughout the GI tract in the lamina propria, with only limited distribution in the surface epithelium or crypt/glandular epithelium. Additionally, counts are tissue specific, with distribution highest in the proximal colon (highest overall value in the

Supplementary data

The following are the Supplementary data to this article.

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Disclosures: This study was not funded. The authors have indicated they have no financial relationships relevant to this article to disclose. The authors have indicated that they have no potential conflicts of interest to disclose.

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