Malignant germ cell tumor diagnosed predominantly in young adults ages 20 to 30. The most common benign germ cell tumor is the mature teratoma, commonly called a dermoid cyst (see Dermoid Cyst).

Primitive germ cell tumors include the dysgerminoma, immature teratoma, endodermal sinus/yolk sac tumor, embryonal carcinoma, and nongestational choriocarcinoma.

Findings involve a solid, mostly isoechoic, but heterogeneous mass with apparent lobulations. The lobulations are caused by inhomogeneous internal echogenicity giving the sonographic appearance of different compartments in this solid tumor. Blood flow is moderate to abundant in most lesions, indicating a high risk of malignancy.

The solid appearance of this tumor makes the differential diagnosis extensive. Struma ovarii (ectopic thyroid tissue, monodermal teratoma) can have a similar appearance although less vascular. Other solid ovarian malignancies should be considered, including metastatic disease to the ovary, lymphoma, and predominantly solid cystadenocarcinomas (although the common cystic portions of these cystadenocarcinomas are not usually seen in dysgerminomas). The extensive blood flow makes the fibroma and mature dermoid unlikely.

Dysgerminomas may present either as palpable adnexal masses or as incidental findings on an imaging study. Occasionally, these tumors display unusually rapid growth, and patients may present with abdominal enlargement and pain caused by rupture with hemoperitoneum or torsion. If the tumor is hormonally active, menstrual abnormalities may occur. These tumors can produce placental alkaline phosphatase and LDH. Thus, in patients with a solid-appearing adnexal mass, assessment of such tumor markers may be helpful. An occasional patient may produce hCG but virtually never produces alpha fetoprotein (AFP). Studies indicate that approximately 75% of women with dysgerminomas present with stage I disease. There is bilateral involvement in approximately 10% to 15% of cases. Because the ultrasound findings are nonspecific, treatment is surgical exploration and resection in virtually all cases. These patients are often young and have not completed their child bearing; therefore, unilateral salpingo-oophorectomy is appropriate and is curative in most cases.