Chordoma
Chordoma is a rare slow-growing neoplasm (cancer) that arises from cellular remnants of the notochord in the bones of the skull base and spine. The evidence for the notochordal origin of chordoma is the location of the tumors (along the neuraxis), the similar immunohistochemical staining patterns, expression of brachyury, and the demonstration that notochordal cells are preferentially left behind in the clivus and sacrococcygeal regions when the remainder of the notochord regresses during fetal life.