Ovarian germ cell tumours

Definition

• Ovarian germ cell tumours arise from primitive germ cells; about 95% are benign mature cystic teratomas and only about 5% are malignant.
• Yolk sac tumour is a malignant primitive germ cell tumour that histologically resembles the mesenchyme of the primitive yolk sac.

Classification

Germ cell and sex cord-stromal tumours

• Most common germ cell tumour: The most common germ cell tumour is the mature teratoma, i.e., the dermoid cyst.
• Malignant germ cell tumours: Malignant germ cell tumours are dysgerminoma, yolk sac tumour, immature teratoma, and choriocarcinoma — typically in young women.
• Sex cord-stromal tumours: Sex cord-stromal tumours include granulosa cell tumour, theca cell tumour, fibroma, and Sertoli-Leydig cell tumour.
• Granulosa cell tumour: The granulosa cell tumour is clinically conspicuous due to oestrogen production with bleeding disorders, endometrial hyperplasia, or precocious puberty.
• Sertoli-Leydig cell tumour: The Sertoli-Leydig cell tumour causes virilisation due to androgen production.

Classification and epidemiology

• Among malignant types, in order of frequency, come dysgerminoma, immature teratoma, yolk sac tumour and mixed germ cell tumour; embryonal carcinoma, choriocarcinoma and malignant struma ovarii are rarer.
• Dysgerminoma accounts for about one third of malignant germ cell tumours; 80–85% of patients are under 30, and it is the most common ovarian tumour diagnosed in pregnancy and the puerperium.
• Malignant germ cell tumours are mostly unilateral, but pure dysgerminoma is bilateral in 10–15%.

Aetiopathogenesis

Aetiology

• Germ cell tumours can arise in dysgenetic gonads, for example in Turner or Swyer syndrome; with a Y chromosome a gonadoblastoma may develop, which undergoes malignant transformation in more than 40%.

Clinical features

• Occasionally the tumours produce hCG and cause signs of precocious puberty.

Histology

• Dysgerminomas are well encapsulated, firm and solid; tumour cells are surrounded by connective tissue containing lymphocytes, and diffuse strong nuclear OCT4 staining is characteristic.
• Schiller-Duval bodies are diagnostic of yolk sac tumour but are found in only about one third of cases.

Diagnosis

Tumour markers

• CA 19-9: The marker CA 19-9 is characteristically elevated in mucinous ovarian tumours and in pancreatic and biliary tract carcinomas.
• CEA: Carcinoembryonic antigen (CEA) is elevated primarily in gastrointestinal carcinomas, suggesting a metastasis in the case of an adnexal finding.
• Granulosa cell tumour: If a granulosa cell tumour is suspected, one measures inhibin B and anti-Müllerian hormone.

• Diagnosis relies on history, examination, ultrasound and the serum markers LDH, AFP and hCG: LDH is typical of dysgerminoma, AFP of yolk sac tumour and hCG of choriocarcinoma.

Keep learning in the app

Further reading (selection)

1. Ovarian Germ Cell Tumors: Pictorial Essay (Diagnostics (Basel) 2022, PubMed Central)
2. StatPearls: Yolk Sac Tumors
3. DocCheck Flexikon, Ovarialtumor
4. DocCheck Flexikon, CA 125

Cross-references