Definition

A rare type of tumor that begins in germ cells (cells that form sperm or eggs) found in areas of the body other than the testicle, ovary, or brain. Most extragonadal extracranial germ cell tumors form either in the sacrum (the large, triangle-shaped bone in the lower spine that forms part of the pelvis) and tailbone, or in the chest area and back of the abdomen. They may be benign (not cancer) or malignant (cancer) and occur most often in children and young adults.