More than 30 different types of ovarian tumors exist, and each could be benign or malignant. These 30 types make up three sub-categories of tumors: Epithelial, Germ Cell, and Sex Cord Stromal.
Benign Epithelial Tumors
Serous adenomas, mucinous adenomas, and Brenner tumors are epithelial tumors. These are the most common form of ovarian tumor. These tumors start on the lining outside the ovary. Most of them are benign.
Malignant Epithelial Tumors
Ninety percent of ovarian cancers are epithelial ovarian carcinomas. When diagnosed with this type of tumor, it is classified by a subtype, grade and stage. This determines how likely it is for the tumor to spread and grow quickly. Women over 50 are more susceptible to this type.
Benign Germ Cell Tumors
Germ cell tumors form in the egg-producing cells of the ovary. Most are benign, and only about 5 percent lead to ovarian cancer. Women under 30 are most commonly diagnosed.
Malignant Germ Cell Tumors
Dysgerminoma is the most common form of malignant ovarian tumor. It usually affects teens and women in their 20s. In the majority of cases, the tumor is limited to the ovary, and patients undergo surgery to have the ovary removed.
Sex Cord Stromal Tumors
Sex Cord Stromal makes up 5 percent of cases and is the least aggressive. In this type, tumors form in tissue that holds the ovary together. This tissue produces estrogen and progesterone. Only about 1 percent of ovarian cancers are sex cord stromal.
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