Hi, Thanks for writing in. The clivus is part of the bone in the inside of the skull. This is a small bone that has a pea sized area in front where the pituitary gland is found. The clivus is a bone located behind the pituitary, A chordoma is a tumor of bone origin and is regularly noted in relation to the clivus. It is part of a family of cancers called sarcoma, which include cancers of the bones, cartilage, muscles and other connective tissue. Chordomas are thought to arise from remnants of the embryonic notochord and might have cell origins since birth and start proliferating at a later age. They are usually slow growing and recur after treatment. Because of their proximity to critical structures biopsy is difficult and requires skilled approach. Often it is diagnosed on CT scan or MRI scan and treatment is given. Having it evaluated in a teaching school will give you more options of treatment and cure.