Light micrograph showing a higher magnification view of nonatypical endometrial hyperplasia. The glands are lined by simple columnar epithelium with an orderly arrangement of nuclei. There is no cytologic atypia. Endometrial hyperplasia (EH) refers to an abundance of endometrial glands. It is defined as abnormal proliferation of the endometrial glands relative to the stroma, leading to an increase in gland to stroma ratio (>1). It is an important cause of abnormal, non-cyclical uterine bleeding and a precursor to the most common type of gynaecologic cancer - endometrial carcinoma (EC), endometrioid type. The most common risk factors are unopposed estrogen effect from anovulatory cycles and exogenous use in postmenopausal women.