Massive endometriosis in two rhesus monkeys

Massive endometriosis was found in two rhesus monkeys during a chronic toxicological experiment. These cases had metastatic lesions in lymph nodes in addition to the foci on the serosal wall of pelvic organs. Invasion to the intestinal mucosal layer was also noted in a case. These observation indicated that endometriosis in the rhesus monkey might behave like a malignant neoplasm.