The following are extreme and rare symptoms of ovarian cysts. They include cases where cysts cause mental illness and extreme weight gain. The mental illness case was featured in Monsters inside me. It is a rare occurrence where dermoid ovarian cysts, teratomas, formed brain cells. This caused white cells to attack the patient's brain cells, leading to intense hallucinations. The video can be found here: http://ovarian-cyst-miracle-101.blogspot.com/2014/04/dermoid-ovarian-cyst-causes-madness-teratoma-symptoms.html