Germ Cell Tumors

Germ cells are specialized types of cells that develop in a fetus (unborn baby) and give rise to other cells needed for reproduction. Their name comes from the word germinate, which means to begin to grow. As a child matures, germ cells eventually give rise to sperm in the testicles of boys or to unfertilized eggs in the ovaries of girls. In rare instances, tumors can form in these germ cells (referred to as gonadal germ cell tumors), which can be either malignant (cancerous) or benign (noncancerous). 

Occasionally, germ cell tumors form from developing sperm or egg cells that travel to other parts of the body, such as the brain, abdomen, lower spine, or the area between the lungs. These tumors are referred to as extragonadal germ cell tumors and are most common in adolescents.