[Diagnostic characteristics of gastric and duodenal eosinophilic gastroenteritis].

<b>Objective:</b> To investigate the diagnostic features of eosinophilic gastroenteritis (EGE) of the stomach and duodenum. <b>Methods:</b> A case-control study was conducted to retrospectively analyze 238 biopsy specimens of gastric and duodenal EGE (75 cases) and 133 biopsy specimens of chronic active gastroenteritis (97 cases) in Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China from 2012 to 2023. The eosinophil count, infiltration site and other pathological features (e.g., infiltration of neutrophils into the epithelium, edema, and increase of background lymphocytes and plasma cells) were examined under a microscope. Chi-square test, chi-square multiple comparison (<i>Bonferroni</i> method) and modified <i>Poisson</i> regression were used to analyze the data. <b>Results:</b> The results showed that there were significant differences in eosinophil count (<i>χ</i>²=43.926, <i>P</i><0.01), location (<i>χ</i>²=31.391, <i>P</i><0.01), neutrophilic infiltration of the epithelium (<i>χ</i>²=5.199, <i>P</i>=0.023), edema (<i>χ</i>²=3.934, <i>P</i>=0.047), and lymphoplasmacytosis (<i>χ</i>²=36.813, <i>P</i><0.01) between the EGE and control cases. The results of Chi-square multiple comparisons showed that eosinophils distributed in clusters or sheets (versus other grades of eosinophil presence) were statistically associated with EGE. When eosinophils infiltrated the epithelium (versus eosinophils in other locations of the mucosa), there was a statistically significant association with EGE. Modified <i>Poisson</i> regression also showed that EGE was more likely to have eosinophilic infiltration of epithelium [<i>RR</i>=1.661,<i>P</i>=0.001,95%<i>CI</i> (1.397,1.973)] and that of muscularis mucosa [<i>RR</i>=1.818,<i>P</i><0.01,95%<i>CI</i> (1.491,2.216)]. <b>Conclusions:</b> The important pathological features for diagnosing EGE of the stomach and duodenum are that eosinophils are clustered or distributed in sheets with epithelial infiltration. However, epithelial infiltration by neutrophils, edema and background lymphoplasmacytosis are relatively rare.