It is difficult to distinguish ovarian germ cell tumors on ultrasound alone. Both solid and cystic lesions with calcification may be present. Dysgerminoma often appears as a hypoechoic mass while other ovarian germ cell tumors often have variable echogenicity. Ovarian teratoma may be further characterized by the presence of sebaceous and hair components arising from the Rokitansky protuberance.

Ovarian mature teratoma

• Ultrasound is the most frequently used modality for the diagnosis.^[1]
• On Ultrasound imaging, it may have variable appearances, however, the three most common appearances from the most common to least common include:^[1][2]
  • Cystic lesion with a projecting tubercle (Rokitansky nodule) into the cyst lumen that is densely echogenic
  • A mass with partial or diffuse echogenicity due to sebaceous material and hair within the cyst cavity
  • A cyst cavity with multiple thin, echogenic bands owing to hair materials

Immature ovarian teratoma

• Ultrasound imaging is not helpful for the diagnosis of immature teratoma.^[3]
• The US finding are usually nonspecific and include:
  • Heterogeneous appearance with partially solid lesion
  • Foci of calcification

Monodermal teratoma

• Struma ovarii:
  • Nonspecific finding on the ultrasound imaging.^[3]
  • A heterogeneous mass which is predominantly solid
  • A complex mass with multiple solid and cystic areas

Dysgerminoma

• They are purely solid (with rare exceptions)^[4]
• Lobulated components with heterogeneous echogenicity and with well-defined borders.

On color and power Doppler ultrasound:

• These tumors are highly vascularized.

Yolk sac tumor

• Heterogeneous echogenicity in the solid portion^[4]
• Septas dividing the cystic portion

Embryonal carcinoma

• There is no specific imaging criteria for embryonal carcinoma.

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