chordoma
Meaning of chordoma: A rare midline bone tumor grown from embryonic leftovers, slow to develop but stubbornly local and prone to returning.
Definition of chordoma
A chordoma is a rare, slow-growing bone cancer that develops from remnants of the notochord, the flexible rod that guides formation of the spine in the embryo and normally disappears before birth. It arises along the midline of the skeleton, most often at the base of the skull or the lowest part of the spine. It invades neighboring tissue and tends to recur.
Where does it come from?
Early in development every embryo has a notochord, a stiff cord that tells the surrounding tissue where the backbone should form. Most of it breaks down before birth, leaving only the soft center of each disc between the vertebrae. Small nests of notochord cells occasionally persist inside the bone itself, and a chordoma grows from one of them. That origin explains its distribution exactly: the tumor appears only where the notochord once ran, in a line from the base of the skull down the spinal column to the tailbone.
Where does it usually appear?
| Site | Typical effects |
|---|---|
| Base of the skull | Double vision, headache, difficulty swallowing |
| Mobile spine | Back pain, nerve compression, weakness |
| Sacrum and tailbone | Low back or buttock pain, bowel and bladder changes |
How does it behave?
Chordoma grows slowly, so symptoms build over months or years and the tumor is often large before anyone finds it. It rarely spreads early, but it pushes into bone, nerves and blood vessels around it, and cells left behind after surgery regrow. Recurrence at the original site, rather than distant spread, is the main problem. Removing the tumor whole with a margin of normal tissue gives the best outlook, and that is hard at the skull base, where the brainstem, major arteries and cranial nerves sit immediately alongside. Radiation is frequently added, often with proton beams, which release their energy over a narrow depth and spare tissue behind the target. Ordinary chemotherapy has little effect on this bone cancer.
How is it recognized under the microscope?
The tumor contains physaliphorous cells, bubbly cells stuffed with fluid-filled spaces that give them a foamy look, sitting in a jelly-like background. A protein called brachyury, made by notochord cells and by almost nothing else, can be stained for and confirms the diagnosis. That marker separates chordoma from cartilage tumors that can look very similar in the same locations.
Used in a sentence
Imaging of the sacrum showed a destructive midline mass later confirmed as a chordoma.
Good to know
Chordoma spreads late but invades locally, so completeness of the first removal largely determines the outcome and recurrence at the original site is the usual pattern of failure.
Word origin
Where “chordoma” comes from
From the Greek chorde, meaning cord or string, after the notochord, with the ending -oma, meaning tumor.