Eosinophilic Gastritis in Children

Clinicopathological Correlation, Disease Course, and Response to Therapy

Huaibin M Ko MD; Raffaella A Morotti MD; Oksana Yershov MS; Mirna Chehade MD; MPH

Disclosures

Am J Gastroenterol. 2014;109(8):1277-1285. 

In This Article

Methods

The study was approved by the Institutional Review Board at the Mount Sinai School of Medicine.

Patient Selection

The Mount Sinai Hospital pathology database was searched for endoscopically obtained biopsies examined between 1 January 2005 and 15 August 2011 with the following keywords: "eosinophilic gastritis," "eosinophilic gastroenteritis," "antral mucosa" and "eosinophils," as well as "fundic mucosa" and "eosinophils." Duplicate cases (from repeat procedures performed on the same patient over time), cases from adult patients (≥18 years of age), and cases where eosinophilic infiltration of the gastric and/or duodenal mucosae were not reported were excluded. Of the remaining cases, further review of the pathology reports and biopsy slides were performed. Reports with no/mild gastric eosinophilia were excluded. In addition, those with known etiologies to their gastric eosinophilia were excluded. These were cases with evidence of Helicobacter pylori infection, parasitic infection, chronic histological changes (mixed inflammatory cellular infiltrates, granulomas, and glandular architectural distortion) indicative of Crohn's disease. In addition, patients with history of solid organ transplantation were excluded, as peripheral eosinophilia and/or EGE have been reported after pediatric organ transplantation.[5,6] Figure 1 summarizes our patient selection strategy.

Figure 1.

Flow chart of patients detailing selection strategy and reasons for exclusion from the study.

Histological Evaluation

Hematoxylin and eosin-stained biopsy slides from all patients were reviewed. Each slide contained two antral and/or fundic biopsies. Although normal values for GI mucosal eosinophils have been documented,[7,8] standardized criteria defining the histological features of EG and EGE are lacking. We defined HEG by marked, diffuse, eosinophilic infiltrates with ≥70 eosinophils per high-power field (HPF, 0.237 mm2) in the antrum and/or fundus, either diffusely or multifocally (involving >3 HPFs). The reason for choosing the above threshold was multifold. In healthy children, the number of eosinophils in the gastric antrum and fundus has been reported to be 0–10 per HPF.[7,8] Eosinophilic infiltrates in EG can be patchy, and the minimum threshold number of gastric eosinophils required for the diagnosis of EG varies among investigators, ranging from 20 eosinophils in one HPF to 30 eosinophils per HPF in at least five HPFs,[9,10] to as high as finding of 80 eosinophils per HPF in EG patients.[11] Therefore, we elected to choose a conservative number of 70 eosinophils per HPF as our diagnostic criterion. Biopsy sections were scanned under the microscope at low power (× 100) for the highest eosinophil concentration, and then the eosinophils were counted in one HPF (×400). An eosinophil count of ≥70 eosinophils per HPF in the maximally infiltrated area was considered satisfactory. This typically corresponded to descriptions used in the reports as "marked," "numerous," "innumerable," "carpets," and "sheets" of eosinophils in the mucosa. Figure 2 illustrates a gastric biopsy from one of the children with HEG.

Figure 2.

Illustrative gastric biopsy from a patient with eosinophilic gastritis. (a) Low-power view of the antral mucosa showing diffuse eosinophilic infiltration in the lamina propria (hematoxylin and eosin stain; original magnification ×100). (b) High-power view of the lamina propria eosinophils (hematoxylin and eosin stain; original magnification ×400).

Pathology reports and slides from children with HEG were also reviewed for any concurrent EoE (peak esophageal eosinophil count ≥15/HPF)[12] and any concurrent hypereosinophilia in the duodenum, ileum, and colon. Hypereosinophilia was defined as ≥50/HPF in the duodenum and ileum and ≥70/HPF in the colon, as past studies have reported an upper limit of normal eosinophil count of approximately 30/HPF in the duodenum and ileum, and 15–50/HPF in the colon; colonic counts being the highest in the cecum and then gradually decreasing more distally.[7,8] Table 1 summarizes the eosinophil counts that we used for our selection criteria. Post-treatment biopsies, when available, were reviewed. Histological response to therapy was defined as gastric eosinophils <10/HPF in all fields, given what has been reported as normal gastric eosinophil counts as detailed above.

Medical Record Review

The following data were collected from patients' medical records when available: demographic characteristics, main symptom at presentation, gross endoscopic findings, atopic status, evidence of sensitization to foods by skin prick testing and/or serum food-specific immunoglobulin E (IgE), presence of comorbidities, evidence of peripheral eosinophilia, evidence of protein-losing enteropathy (PLE), type of therapy received, and clinical response.

Intestinal Mast Cell Determination

To investigate whether there is any role for intestinal mast cells in PLE in our patients with HEG without concurrent duodenal eosinophilia, we performed immunohistochemical staining on duodenal biopsies for tryptase, a mast cell mediator. We were able to retrieve formalin-fixed paraffin-embedded duodenal biopsies on six of our patients without duodenal eosinophilia and without PLE and one without duodenal eosinophilia but with PLE. Briefly, 3-μm duodenal sections were deparaffinized and rehydrated. Antigen retrieval was achieved by enzymatic digestion with trypsin (Sigma-Aldrich, St Louis, MO). Endogenous peroxidase was blocked by treatment with hydrogen peroxide. Endogenous biotin was blocked by incubating the sections with avidin followed by biotin (DAKO, Carpinteria, CA). Sections were then incubated with the primary antibody, mouse anti-human tryptase (DAKO), with mouse IgG1 as its isotype control, followed by a biotinylated secondary antibody. Streptavidin-peroxidase complex and substrate-chromogen solutions were used for staining. Hematoxylin was used as a counter stain. Sections were scanned under the microscope under low power (×100) for the highest mast cell (tryptase-positive cell) concentration, and then mast cells were counted in one HPF (×400). Presence or absence of mast cell degranulation in the entire section was also recorded.

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