Germ cell tumors arise most commonly the pineal region and the majority of remainder arise in the suprasellar region.
Germ cell tumors are located along the midline, from the pineal to the coccyx.
Embryonal carcinomas, yolk sac tumors, and choriocarcinomas mainly occur in the pineal region. 68% of non-germinoma germ cell tumors are located within the pineal region.
Extension
Local:
- Pineal tumors may expand locally, compressing the mesencephalon and the brain stem.
CSF Dissemination:
- Multifocal disease (or subependymal spread) present at diagnosis in about 10% of patients with germinoma.
- Tumors will often invade the 3rd ventricle and the spinal cord via infiltration of the hypothalamus or the CSF channels. This pattern of spread is most common with endodermal sinus tumors and choriocarcinomas.
- CSF cytology positive at diagnosis in about 10% of patients with germinoma and 10-15% of patients with non-germinoma GCT.
- Pineal region germ cell tumors are more likely to be associated with CSF dissemination than tumors in other sites.
- Spinal metastases are particularly common in patients with endodermal sinus tumors.
Systemic dissemination:
- Very uncommon with CNS germ cell tumors.
Tumor spread via a ventriculoperitoneal shunt, bringing tumor cells into the abdomen and pelvis has been documented.
Tumor type and common growth pattern:
Tumor |
Growth Pattern |
Grows into 3rd ventricle May invade:
Spread by direct extension or metastasis |
|
Embryonal carcinoma |
Extensive metastases throughout CSF pathway |
Choriocarcinoma |
Infiltrates adjacent brain, especially:
|
No intracranial dissemination Distal subarachnoid metastasis may be observed |
|
Highly malignant and infiltrative |
|
May disseminate along CSF pathway |
