Germ cell tumors are uncommon neoplasms that develop from the primitive cells that give rise to eggs and sperm. These tumors most commonly develop in the ovaries and testicles but may occur anywhere in the body, including the brain. Germ cell tumors of the brain may be noncancerous or cancerous, with the majority presenting in children and young adults. Boys are affected more commonly than girls, with an increased incidence in children of Asian descent.
Germinomas
Germinomas are the most common germ cell tumors of the brain, according to the medical reference website PathConsult DDx Fundamentals. These tumors typically arise in or near the pineal gland, located in the middle of the underside of the brain. Pineal germinomas commonly block the flow of cerebrospinal fluid, causing an accumulation of the fluid within the brain termed hydrocephalus, according to the UCLA Health System Department of Neurosurgery. Increased pressure associated with hydrocephalus typically causes nausea, vomiting and headaches. Other possible symptoms of pineal germinomas include an inability to look upward, unsteadiness and double vision.
Radiotherapy is generally an effective treatment for brain germinomas. A narrowly focused form of radiotherapy called stereotactic radiosurgery is commonly used. Certain types of brain germinomas may require a combination of radiotherapy and chemotherapy.
Teratomas
Teratomas are unusual tumors composed of a highly variable mixture of types of body cells. Brain teratomas may be present at birth, a condition called congenital intracranial teratoma. In a 2010 article published in BMJ Case Reports, Drs. Ruppa Geethanath and Fattma Abdel-Salam note that teratomas are the most common type of congenital brain tumor.
Mature teratomas, also known as benign teratomas, commonly contain skin and related tissues and substances, including hair and oil-producing glands. Other tissue types may also be present, including cartilage, bone, muscle and glandular tissue.
Brain teratomas most commonly arise near the pineal gland or in the suprasellar area just above the pituitary gland, according to the Chicago Institute of Neurosurgery and Neuroresearch. Possible symptoms include nausea, vomiting, headaches, visual disturbances and decreased consciousness. Surgery, radiotherapy, chemotherapy or combination treatment may be required, depending on the location and nature of the tumor.
Mixed Non-germinomas
Mixed non-germinomas are the least common of the germ cell brain tumors. They include yolk sac tumors, embryonal carcinomas and choriocarcinomas. Similar to germinomas and teratomas, mixed non-germinomas typically occur in the midline areas of the brain, including the pineal and suprasellar regions.
In an article published by the Childhood Brain Tumor Foundation, Dr. Jonathan Finlay reports that the presence of substances known as tumor markers can aid in the diagnosis of mixed non-germinomas of the brain. Elevated blood or cerebrospinal fluid levels of alpha-fetoprotein are suggestive of a yolk sac tumor. Similarly, elevated levels of human chorionic gonadotropin raise suspicion for choriocarcinoma. Finlay notes that treatment of mixed non-germinoma of the brain typically involves a combination of chemotherapy and radiotherapy.
References
- PathConsult DDx Fundamentals: CNS Germ Cell Tumors
- UCLA Health System Neurosurgery: Germinoma
- "BMJ Case Reports"; Congenital Intracranial Teratoma; Ruppa Mohanram Geethanath, Fattma Abdel-Salam; May 2010
- Chicago Institute of Neurosurgery and Neuroresearch: Teratoma
- Childhood Brain Tumor Foundation: Germ Cell Tumors of the Brain
