Dermoid Tumors. Dermoid tumors are benign growths that occur when an egg begins to develop without fertilization by a sperm; they can contain hair, teeth, and cartilage. They are easily removed by surgery.
Borderline Ovarian Tumors. About 15% of ovarian tumors are referred to as "borderline" because their appearance and behavior under the microscope is between benign and malignant. These tumors are often referred to as carcinomas of low malignant potential because they rarely metastasize or cause death. Even when borderline carcinomas do spread outside the ovary, only 10% to 20% are fatal.