Clinical meaning
Endometrial polyps are localized overgrowths of endometrial glands, stroma, and blood vessels that project from the endometrial surface into the uterine cavity. They are extremely common, affecting 10-40% of women with abnormal uterine bleeding (AUB), and their prevalence increases with age, peaking in the perimenopausal period. At the molecular level, endometrial polyps demonstrate autonomous proliferative behavior driven by several key mechanisms. Polyp tissue shows overexpression of estrogen receptor alpha (ERα) and reduced expression of progesterone receptors (PR-A and PR-B) compared to adjacent normal endometrium. This receptor imbalance creates localized estrogen hypersensitivity - polyp tissue proliferates in response to circulating estrogen while being relatively resistant to the anti-proliferative effects of progesterone. During the secretory phase, while normal endometrium undergoes progesterone-mediated differentiation, polyp tissue continues to proliferate. Aromatase (CYP19A1) is overexpressed in polyp stromal cells, enabling local conversion of androgens (androstenedione, testosterone) to estrogens (estrone, estradiol) through intracrine and paracrine mechanisms. This creates an autonomous local estrogen microenvironment that drives polyp growth independent of systemic estrogen levels - explaining why polyps can develop and persist even in postmenopausal women with low circulating...