LAUSR

Endometrial hyperplasia is differentiated into benign or premalignant. Two histological classifications are used for this purpose: World Health Organization (WHO) classification, based on cytological atypia, disregarding glandular complexity, and endometrial intraepithelial neoplasia (EIN) classification, based on several different parameters. B‐cell lymphoma 2 (Bcl‐2) loss has been studied as immunohistochemical marker with the aim of improving the differential diagnosis between benign and premalignant hyperplasia. We aimed to evaluate: (A) Bcl‐2 loss as marker of endometrial precancer, by assessing it in proliferative endometrium, benign hyperplasia, premalignant hyperplasia, and endometrial cancer; (B) the diagnostic accuracy of Bcl‐2 in the differential diagnosis between benign and premalignant endometrial hyperplasia; (c) how the results change according to the histological classification and the thresholds of Bcl‐2 expression used.