Ovarian leiomyoma and follicular cysts. Cut specimen of an ovary showing leiomyoma, a benign tumour, and benign follicular cysts. The leiomyoma is the large white fibrous-looking body filling much of the ovary. Such tumours originate from smooth muscle and are benign but may undergo malignant change. They occur most commonly in the uterus wall as fibroids. The cysts seen here are simple benign follicular cysts and are very commonly seen in surgically removed ovaries. Provided malignancy has not caused the tumour cells to spread leiomyoma is treated by surgical removal and prognosis is good.