Chronic Endometritis, a Common Disease Hidden Behind Endometrial Polyps in Premenopausal Women: First Evidence From a Case-Control Study.

STUDY OBJECTIVE: To investigate the correlation between endometrial polyps (EPs) and chronic endometritis (CE). DESIGN: Single-center retrospective case-control study. SETTING: Academic center. PATIENTS: A total of 480 premenopausal women with abnormal uterine bleeding (AUB) were enrolled. Group A included 240 women suffering from EPs (diagnosed by hysteroscopy and histology), and group B included 240 patients without EPs at hysteroscopy. INTERVENTIONS: In group A, 2 separate samples were obtained from the EPs (group A polyps) and endometrium (group A endometrium). In group B, a single sample of endometrial tissue was evaluated (group B endometrium). All tissue samples were subjected to immunohistochemistry for CD-138 for plasma cell identification. MEASUREMENTS AND MAIN RESULTS: The primary study endpoint was to compare the rates of CE in group A endometrium versus group B endometrium. The secondary endpoint was to evaluate the consistency in CD-138 immunoreactivity between group A polyps and compared with group A endometrium. A higher prevalence of CE was observed in group A endometrium compared with group B endometrium (p < .0001). The total percentage of EPs showing CD-138 positivity was 76.7% (184 of 240). CE was more frequent in women with CD-138+ EPs compared to those with CD-138- EPs (p < .0001). CONCLUSIONS: EPs were commonly associated with CE in the premenopausal women suffering from AUB. Moreover, the majority of EPs were positive for CD-138 staining, suggesting a possible hidden association between chronic inflammation and EPs.