Germ cell tumours occur when abnormal germ cells grow in an uncontrolled way.
A germ cell is the type of cell that develops into eggs (in the ovaries) or sperm (in the testicles). Germ cell tumours can develop before or after birth, and can occur in the ovaries or testicles, or in other parts of the body. This is because sometimes, when babies are developing in the womb, germ cells travel to other parts of the body. Germ cell tumours can release hormones or enzymes that can cause signs and symptoms.
Germ cell tumours that form in the ovaries or testicles are called gonadal germ cell tumours. Those that form in the brain or spinal column are called intracranial or intraspinal germ cell tumours, and those that form in other parts of the body are called extracranial, extragonadal germ cell tumours. Germ cell tumours that are extracranial and extragonadal tend to form along the midline of the body, such as in the bottom of the spine, at the back of the belly, between the lungs or on the neck.
Germ cell tumours can be 1 of 3 types:
- Mature teratomas are benign tumours that are not likely to become cancerous. They usually occur in the bottom part of the spine in babies, or in the ovaries of girls when they reach puberty. These are the most common type of extracranial germ cell tumours.
- Immature teratomas might become cancerous. They usually occur in the bottom part of the spine in babies, or in the ovaries of girls when they reach puberty. They can contain several types of cells, such as bone, hair and muscle.
- Malignant germ cell tumours are cancerous. They are divided into germinomas and nongerminomas, depending on the type of hormone they release. Germinomas are the most common type of intracranial germ cell tumour.