Abstract
PURPOSE: To investigate the histopathological association between chronic endometritis (CE) and adenomyosis, focusing on basal endometrial alterations and the potential involvement of tissue injury and repair (TIAR) mechanisms. METHODS: This retrospective case-control study included 146 propensity score-matched hysterectomy specimens (73 adenomyosis, 73 controls). CE was diagnosed via CD38 immunohistochemical staining, identifying ≥ 5 plasma cells per high-power field. Basal endometrial thickness was measured digitally at the endo-myometrial junction. Basal endometrial loss was defined as the absence of the basal layer in at least two of three regions. RESULTS: CE was significantly more frequent in the adenomyosis group (23.3%) than in controls (9.6%; p = 0.028). Basal endometrial loss, observed in 23.3% of cases, was strongly associated with CE (47% vs. 7.1%; p < 0.001). In patients with measurable thickness, a 0.15 mm cutoff predicted CE with AUC 0.888 (sensitivity 83.3%, specificity 86.9%). In multivariate analysis, basal endometrial loss was an independent risk factor for CE (adjusted OR 10.45, 95% CI 4.12-26.51; p < 0.001). CONCLUSIONS: CE is significantly associated with adenomyosis. Basal endometrial loss may mediate this relationship through TIAR-related mechanisms, suggesting CE as a potential therapeutic target in adenomyosis.