Immature ovarian teratoma

Immature ovarian teratoma is an uncommon ovarian germ cell tumour. They differ from mature ovarian teratomas (dermoid cysts) both histologically by the presence of immature tissue, and clinically by their more malignant behaviour.

Epidemiology

They are considerably less common than mature ovarian teratomas, representing less than 1% of ovarian teratomas¹. They also affect a younger age group, occurring most often in the first 2 decades of life (accounting for 10-20% malignant ovarian tumours in this age group).

Clinical presentation

Presentation may be with a palpable pelvic mass or less commonly with abdominal pain ².

Pathology

An immature cystic teratoma is characterised by the presence of immature or embryonic  tissue, as well as the mature tissue elements seen in a mature teratoma. The proportion of immature neuroepithelium present correlates with the tumour grade (and hence prognosis) ⁵.

Macroscopically, immature teratomas are large, encapsulated masses which have a prominent solid component. As well as this, they may feature many of the components seen in a mature teratoma, such as hair, cartilage, bone and calcification.

Associations

• ipsilateral mature cystic teratoma: ~25% ¹
• contralateral immature teratoma: ~10% ¹

Markers

• usually does not produce beta-HCG
• serum AFP elevation in 50% ²

Radiographic features

The imaging appearance is typically of a large, heterogeneous mass with a prominent solid component. However, the spectrum of appearances ranges from a predominatly cystic to a predominantly solid mass. Immature teratomas tend to be larger than mature cystic teratomas at initial presentation.

Extension through the tumour capsule may be present.

Immature teratoma may metastasise to peritoneum, liver or lung. Metastasis to brain has also been reported ⁷.

Ultrasound

Ultrasound appearance can be as a heterogeneous adnexal mass although is non-specific. Calcifications may be present.

CT/MRI

The presence of a prominent solid component containing calcifications and small foci of fat is suggestive. Cystic components may contain serous, mucinous, or fatty sebaceous material. Haemorrhage may be present.

Treatment and prognosis

Treatment is generally with oophorectomy, and if distant metastases are present, postoperative chemotherapy. Chemotherapeutic retroconversion is a phenomenon where the teratoma or its metastasis post radiotherapy become more histologically mature than the primary lesion.

Prognosis depends on stage.

Complications

• peritoneal rupture
• torsion

Differential diagnosis

On imaging consider:

• mature ovarian teratoma
  • tend to be smaller with more cystic change
  • no evidence of metastases

See also

• ovarian tumours

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