Types. There are several different types of ovarian cysts out there. These include dermoid cysts and endometrioma cysts. The most common type is the functional cyst. The follicle cyst occurs when an egg is in a sac which is called the follicle. This follicle breaks open to release the egg. In some cases, the follicle does not open. The fluid that is left inside the follicle can become an ovarian cyst. The corpus luteum cyst occurs when the follicle sac does not dissolve when releasing an egg. The fluid can develop inside the sac, and accumulate, making the cysts.