Benign Notochordal Cell Tumor, from the CureRays guide library.

A benign notochordal cell tumor is a harmless growth inside a spinal or skull-base bone, made of leftover cells from the notochord; most are found by chance, cause no symptoms, and need only watchful imaging rather than surgery or radiation.

What it is.

Before birth, a structure called the notochord guides the spine to form, then mostly disappears. Tiny clusters of notochord cells can remain inside the bones of the spine and skull base. When these cells form a small, contained growth, it is called a benign notochordal cell tumor (BNCT). These are almost always discovered by accident on an MRI or CT done for another reason, and they typically cause no pain or problems. They sit entirely within the bone, stay small, and do not invade surrounding tissue. The important reason doctors pay attention to them is their close cousin: chordoma, a malignant tumor that arises from the same notochord cells. BNCT is thought to be a possible precursor to chordoma, so the goal is to confidently tell the two apart — a benign tumor that can simply be watched, versus a cancer that needs aggressive surgery and high-dose radiation.

How radiation treats it.

Radiation is not part of treating a benign notochordal cell tumor, because the growth is harmless and does not need to be destroyed. If, however, follow-up reveals that a lesion is actually a chordoma, radiation becomes very important: chordomas resist ordinary x-rays, so doctors use high-dose proton or carbon-ion beams, which deliver intense radiation precisely to the tumor and then stop, protecting the spinal cord and brainstem just millimeters away. That treatment is painless, given in short daily sessions, and leaves no radioactivity in the body.

The ways we can treat it.

Radiation — not used for benign tumors. A true benign notochordal cell tumor needs no radiation. Radiation enters the picture only if the lesion turns out to be a chordoma, where high-dose proton or carbon-ion beams are central to treatment.

MRI monitoring. Repeat MRI is the key tool. It tracks size and signal characteristics over time so any shift toward chordoma-like behavior is caught early, before symptoms develop.

Questions we hear often.

I was told I have a notochordal tumor — is it cancer? A benign notochordal cell tumor is not cancer. It is a harmless cluster of leftover embryonic cells inside a bone. The reason your doctor is paying attention is that it shares an origin with chordoma, a cancer, so they want to be sure which one you have.

Do I need surgery or radiation? Usually neither. The standard for a classic benign notochordal cell tumor is to monitor it with periodic MRI scans. Surgery and radiation are reserved for lesions that turn out to be — or change into — chordoma.

How will my doctor know if it becomes a chordoma? Follow-up MRIs look for warning signs: growth, destruction of the surrounding bone, contrast enhancement, or a mass pushing outside the bone. If any appear, you'll be referred to a specialist center for evaluation and, if needed, treatment.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.