Clinical and Histopathological Correlates of Endometrial Proliferative Lesions in Perimenopausal Women: A Retrospective Study with Internal Validation of a Risk Model

<b>Background:</b> Endometrial proliferative lesions are common in the menopausal transition and carry a measurable risk of carcinoma. Early risk stratification may guide evaluation and follow-up. <b>Methods:</b> We performed a single-center retrospective study of 315 women aged 45-55 years (May 2021-May 2024) at a private clinic in Bucharest. Lesions were classified per WHO 2014 as hyperplasia without atypia, atypical hyperplasia/endometrial intraepithelial neoplasia (AH/EIN), or adenocarcinoma; "advanced pathology" was defined as AH/EIN or adenocarcinoma. Clinical comorbidities and transvaginal ultrasound endometrial thickness were recorded. Associations were tested with χ²; odds were estimated with multivariable logistic regression (adjusted ORs), with a modified Poisson sensitivity analysis for adjusted relative risk. Thickness differences were compared by one-way ANOVA, and severity correlations by Spearman's ρ. Internal validation used 1000-bootstrap resampling. <b>Results:</b> Hyperplasia without atypia comprised 74.6% of cases, AH/EIN 20.0%, and adenocarcinoma 5.4% (advanced pathology 25.4%). Diabetes was independently associated with advanced pathology (aOR 2.75; 95% CI 1.14-6.61; <i>p</i> = 0.0237), while a history of non-atypical hyperplasia was inversely associated (aOR 0.31; 95% CI 0.13-0.72; <i>p</i> = 0.0068). Obesity showed a borderline association (aOR 1.79; 95% CI 0.98-3.26; <i>p</i> = 0.058), and long-term oral contraceptive use also approached significance (aOR 0.42; 95% CI 0.18-1.00; <i>p</i> = 0.051). Endometrial thickness increased stepwise with histopathological severity (ANOVA <i>p</i> < 0.0001; η² = 0.44) and correlated with ordered severity (ρ = 0.634). The multivariable model showed moderate discrimination (AUC 0.68; optimism-corrected 0.66) with acceptable calibration (slope 0.92; Hosmer-Lemeshow <i>p</i> = 0.052) and overall accuracy (Brier 0.18). <b>Conclusions:</b> In perimenopausal abnormal bleeding, metabolic comorbidities-especially diabetes-together with increased endometrial thickness identify women at higher risk of AH/EIN or carcinoma. Histopathology remains the diagnostic reference. The model can aid clinical prioritization but requires external validation and should not be used as the sole basis for decisions.