Chocolate Cyst

A chocolate cyst, or endometrioma, is a mass or lump that is found on or inside the ovaries. This type of cyst is filled with chocolate-colored fluid and is caused by endometriosis. Endometriosis is a condition in which tissue that normally lines the inside of the uterus grows outside of the uterus. This misplaced tissue can attach to the ovaries, fallopian tubes, and other pelvic organs.