Endometrial polyps and hyperplasia produced in an aged monkey with estrogen plus progesterone.

A female rhesus monkey past menopause was given a total of 120 mg estradiol benzoate by sc implantation over a 1 1/4-year period plus 1630 mg of progesterone in 5 mg doses twice daily for 6 days a week during the latter period of drug treatment. 4 months after the final implantation there was a bloody vaginal discharge which became continuousd3 months later until the monkey unable to sit or stand was killed. Gross findings at necropsy included an enlarged uterus with a dark-colored tumor rising 2.2 cm above the endometrial surface thickened endometrium and a hemorrhagic cyst on the right ovary. Histological examination revealed the tumor to be a hemorrhaging polyp with advanced necrosis at the apex various blood cells and disintegrating endometrial glands at the middle and estrogen-type endometrial hyperplasia at the base. The endometrium showed cystic hyperplasia with thickening and proliferation of the blood vessels. Changes were also noted in the cervix vagina uterine tube ovary and mammary glands.