The symptoms of a germ cell brain tumor depend on where it is located. Correct diagnosis is key, since a germ cell tumor may mimic a host of other brain tumors, including optic pathway gliomas, craniopharyngiomas, pineal parenchymal tumors (such as pineoblastoma or pineocytoma), and pituitary tumors, all of which require different treatments.
Germ cell tumors located in the parasellar region (within the hypothalamus or pituitary gland) frequently cause hormonal dysfunction. An early hallmark of these tumors is a condition in which the body loses the ability to regulate water balance, resulting in polyuria (excessive urination) and polydipsia (excessive thirst). Since that area of the brain is also close to the optic nerves and optic chiasm, germ cell tumors in this location also frequently cause changes in vision. Primary germ cell tumors in this location are more frequent in females.
On the other hand, germ cell tumors in the pineal region of the brain usually present with nausea, headache, and double vision. The nausea and headache arise from a condition called occlusive or obstructive hydrocephalus, a blockage of normal cerebrospinal fluid (CSF) flow. The double vision associated with pineal region tumors results from compression of critical areas of the brain that regulate balanced eye movements and upward gaze. Primary germ cell tumors of the pineal region are more frequent in males.
Rarely, these tumors can be synchronous in both the parasellar and pineal region. This “bi-focal” tumor distribution is nearly diagnostic for primary CNS germ cell tumors.
Reviewed by Mark M. Souweidane, MD
Last reviewed/last updated: December 2020
