extracranial germ cell tumor

(EK-struh-KRAY-nee-ul jurm sel TOO-mer) A rare cancer that forms in germ cells in the testicle or ovary, or in germ cells that have traveled to areas of the body other than the brain (such as the chest, abdomen, or tailbone). Germ cells are reproductive cells that develop into sperm in males and eggs in females.