If a cyst breaks open, it can cause pain in the back of the knee or down the leg. If a cyst is large enough, it can lead to swelling in the leg and foot. Ovaries — When ovarian cysts rupture, they cause sudden, severe pain in one side of the lower abdomen or upper pelvis. Ovarian cysts are associated with menstrual spotting and irregular menstruation. Breasts — Most breast cysts do not cause any symptoms. Others are tender to the touch.