Germ cell tumors (GCTs) include two main categories: germinomas and nongerminomatous germ cell tumors (NGGCTs). The latter encompasses embryonal carcinoma, choriocarcinoma, yolk sac tumor, and mature/immature teratomas, with all except mature teratomas being malignant. These tumors predominantly occur in children, accounting for 0.3%–15% of pediatric intracranial tumors, and show a marked male predominance with a male-to-female ratio of 3:1. Most tumors arise in midline regions of the diencephalon, with the pineal region accounting for 51% and the suprasellar region for 30%. Multifocal tumors are observed in 8.5% of cases. In males, these tumors are more common in the pineal region, whereas in females, they are more frequent in the suprasellar region.
Tumors compressing the tectal region of the midbrain can result in an upward gaze palsy. Tumors located in the suprasellar region may lead to visual field defects, impaired vision, diabetes insipidus, and hypopituitarism. Compression or obstruction of the aqueduct or the Monro foramen of the lateral ventricles may cause obstructive hydrocephalus accompanied by increased intracranial pressure and ataxia. Tumors in the basal ganglia region may manifest as hemiparesis and sensory deficits on one side of the body. Key molecular markers associated with germ cell tumors include beta-human chorionic gonadotropin (β-HCG), alpha-fetoprotein (AFP), and placental alkaline phosphatase (PLAP).
The treatment approach for germinomas typically involves a combination of intravenous chemotherapy and moderate-dose radiotherapy. NGGCTs generally require multimodal therapy that includes surgery, radiotherapy, and chemotherapy. For mature teratomas, complete surgical resection is curative, and additional radiotherapy or chemotherapy is unnecessary. The 10-year survival rate for isolated germinomas exceeds 90%, while prognoses for embryonal carcinoma, yolk sac tumor, and choriocarcinoma are extremely poor.