Ovarian neoplasms can be divided into:

• epithelial tumors: serous, mucinous, endometrioid, clear cell, Brenner and undifferentiated
• germ cell tumors: teratoma (mature or immature), dysgerminoma, endodermal sinus tumor,  embryonal cell carcinoma and choriocarcinoma
• sex cord-stromal tumors: granulosa-stromal cell tumors (granulosa cell tumor, fibrothecoma and sclerosing stromal tumor), Sertoli-stromal tumors (Sertoli-Leydig cell tumor) and steroid cell tumors
• other tumors: metastatic tumors

Epithelial tumors are the most common and represent about 60% of all ovarian tumors. Dysgerminoma (type of germ cell tumors) is found mainly in young females. It is considered as the ovarian counterpart of seminoma of the testis. It is not associated with endocrine hormone secretion unless syncytiotrophoblastic giant cells are present which secrete HCG (5% of cases). Calcification can be present. Imaging findings are characterized by the presence of multi-lobulated solid masses with prominent fibrovascular septa.