This ovary cyst can be a functional cyst, which often forms during the normal menstrual cycle.
Each month, a woman's ovaries grow tiny cysts that hold the eggs.
After releasing the eggs, the sac should dissolve.
In some cases, this sac won't dissolve, but, filled with fluid and grow like a big cyst, causing symptoms.
Other possible scenario, is that your daughter has endometriomas, cysts that develop in women who have endometriosis (the growth of cells similar to those that form the inside of the uterus, but in a location outside of the uterus).
Main complaints of endometriosis are heavy, very painful, long menstrual periods with lower back and lower abdomen pain.
There are many conditions of infective and inflammatory (noninfective) origin that can cause formation of lung cyst.
Was your daughter performed CT?