An ovarian cyst is a sac or pouch filled with liquid that develops on an ovary. The most common are the ovarian functional cysts, which develop as part of the ovulation process. There are two types of ovarian functional cysts: follicular cysts, which are the ones that develop when the follicle does not open to release the egg, and corpus luteum cysts, which develop if the follicle that held the egg is sealed after release. Usually, there is no need for specific treatment since they produce mild symptoms and disappear on their own in about 6 or 7 weeks. In addition, the cysts are common in women of childbearing age, and are usually benign, but can also be malignant or cancerous. In many cases it may require surgery: in the case of benign cysts the surgeon can remove just the ovarian area that is affected, through a laparoscopic intervention. However, in the case of malignant cysts, surgeons often opt to remove the entire ovary.