[670] Eosinophilic Gastritis: Histopathologic Characterization and Quantification of the Normal Gastric Eosinophil Content.

Shelby D Melton, Robert M Genta, Thida Lwin. VA North Texas Health Care System, Dallas; University of Texas Southwestern Medical Center, Dallas; Caris Life Sciences, Irving, TX

Background: There are no published criteria for the diagnosis of eosinophilic gastritis, and information about normal eosinophil counts in the gastric mucosa is limited. Therefore, pathologists are often uncertain as to when and how increased eosinophils in gastric biopsies should be reported. The aims of this study were: 1) to determine the normal gastric eosinophil content in histologically unremarkable gastric biopsies; and 2) to investigate the clinicopathologic features of eosinophilic gastritis.
Design: From an electronic database we extracted 60 patients (median age 50; range 4-83; 34 females) whose gastric biopsies over a 2-year period were diagnosed as having elevated mucosal eosinophils. For each study patient we then identified 2 or 3 age-, sex-, and ZIP code-matched control subjects who had unremarkable gastric biopsies during the same period. We reviewed all slides and counted eosinophils in the lamina propria in 5 high-power fields. Involvement of the muscularis mucosae or submucosa and sheets of eosinophils were noted, and infiltration of the gastric epithelium was scored on a scale of 0 to 2. Results are reported in eosinophils/mm².
Results: Eosinophil counts from gastric biopsies of study patients and controls are listed in Table 1.

	Study patients	Controls
	n = 60	n = 135
Median density (eos/mm²)	180	6
Mean density (eos/mm²)	218	4.9
S.D.	139	5.3
Range	4 - 665	0 - 34.6

The normal eosinophilic count in this geographically diverse sample of the US population was ∼6 eos/mm². There was no significant difference between eosinophil counts in biopsies from the antrum and corpus, and no significant variation by age or geographic location. Amongst study patients, the average count was 218 eos/mm²; sheets of eosinophils were seen in 38 patients; 27 had involvement of the muscularis mucosae or submucosa; and 52 had intraepithelial eosinophils. None showed evidence of H. pylori by immunohistochemistry. No distinct presenting symptoms or endoscopic features were identified.
Conclusions: This study suggests that the normal gastric eosinophilic counts in the US population are usually <12 eos/mm² and specimens with >40 eos/mm² (or >30 eos/HPF) in at least 5 high-power fields represent a definite departure from normal (mean + 7SD). We recommend using the term “histologic eosinophilic gastritis” for the diagnosis of such gastric biopsies. Clinical correlations may emerge if sufficient numbers of cases are diagnosed and analyzed.
Category: Gastrointestinal

Tuesday, March 1, 2011 8:00 AM

Platform Session: Section E, Tuesday Morning