Endometrioid cyst: : Part of the condition known as endometriosis, this type of cyst is formed when endometrial tissue (the mucous membrane that makes up the inner layer of the uterine wall) grows in the ovaries. It affects women during the reproductive years and may cause chronic pelvic pain associated with menstruation.
Women with endometriosis may have problems with fertility.
Endometrioid cysts, often filled with dark, reddish-brown blood, may range in size from 0.75-8 inches.
Endometrioma is also referred to as an endometrioid cyst.