Simple hyperplasia without atypia is characterized by cystically dilated glands of various shapes and sizes. There is mild increase in gland-to-stroma ratio. Progression to adenocarcinoma occurs only in about 1% of cases. Endometrial hyperplasia is the result of excessive estrogenic stimulation of the endometrium. Associated conditions include obesity, polycystic ovary disease (including Stein-Leventhal syndrome), functioning granulosa cell tumors of ovary, and exogenous estrogens etc.