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Intracranial germ cell tumours

contributed by Dr Frank Gaillard on April 1, 2009

System: Central Nervous System

Intracranial germ cell tumours are a heterogenous group with variable imaging appearances, biology, response to treatment and prognosis. They make up approximately 0.4 to 3.4%of brain tumours in the western population, although the incidence is up to 8 times higher in the far east (as is the rate of testicular tumours).

Location and demographics

These tumours tend to cluster in the midline, with a predilection of the pineal region (see pineal mass for differential diagnosis) and the suprasellar region.
Controversy persists as to whether multifocal lesions, found at the time of diagnosis in 5 - 10% of patients, represents synchronous tumours or spread. 

In general males are more frequently affected than females, and this is most evident in non-germinomatous tumours of the pineal.

Over all peak in incidence around the time of puberty - somewhat earlier for nongerminomatous germ cell and somewhat later for germinomas.

  • pineal region : twice as common as all other sites
  • suprasellar region
    • next most common
    • suprasellar germinomas more common in women
  • floor of third ventricle
  • basal ganglia : more likely germinoma
  • thalamus : more likely germinoma
  • fourth ventricle

WHO classification

see  WHO classification of CNS tumours for complete list.

Radiographic features

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Treatment and prognosis

In general biopsy is required as treatment and prognosis will vary with histology (whereas it is independent of location). Agressive surgical debulking is of unproven benefit and carries significant morbidity given the usual locations of these tumours.

Germinomas are exquisitely radiosensitive, with cure achieved with radiation alone iin 90% of patients.

Non-germinomatous tumours have much worse prognosis with survival rates ranging between 40% and 70%.

Teratoma prognosis depends on degree of differentiation (mature vs immature) and whether malignant transformation on a component is present (uncommon). In general mature teratomas are indolent, whereas immature teratomas do poorly, with survival rates ranging between 50% and 70%.