ovarian dysgerminoma

Ovarian dysgerminomas are a type of germ cell tumor of the ovary. They are the most common malignant germ cell tumors of the ovary and are thought to account for ~1% of all ovarian neoplasms .

Epidemiology

They are rare ovarian tumors that occur predominantly in young women (majority occurring in the 2 to 3 decades ).  Approximately 10-20% of cases occur in pregnancy.

Pathology

The tumor is thought to arise from primordial germ cells and is considered the ovarian counterpart of seminoma of the testis. They are usually solid and multi-lobulated.

Markers

The tumors are usually hormonally inert and in their pure form not associated with endocrine hormone secretion. However, syncytiotrophoblastic giant cells, which produce HCG, are present in 5% of dysgerminomas and can cause elevation of serum HCG levels. LDH can also be raised making it useful in diagnosis and post-operative follow-up of ovarian dysgerminoma .

Variants

Approximately 15% of tumors can contain other malignant germ cell variants in which instance they are termed malignant mixed germ cell tumors of the ovary .

Laterality

Approximately 10-17% of tumors can be bilateral.

Radiographic features

Ultrasound

May be seen as a septated ovarian mass with varying echotexture. Color Doppler interrogation may show prominent flow signals within the fibrovascular septa .

CT

Calcification may be present in a speckled pattern. Characteristic imaging findings include multilobulated solid masses with prominent fibrovascular septa. Post-contrast imaging can often show enhancement of the septae.

MRI

Tumors are often seen divided into lobules by septa.

Reported signal characteristics include:

  • T2: the septae are often hypointense or isointense
  • T1 C+ (Gd): the septae often show marked enhancement  

See also