Meningioma

A meningioma is a tumor that forms in your meninges, which are three layers of tissue that cover and protect your brain and spinal cord. Meningiomas originate from arachnoid cells in particular, which are cells within the thin, spiderweb-like membrane that covers your brain and spinal cord. This is one of three layers that make up the meninges.

Most meningiomas aren’t cancerous (benign), though they can sometimes be cancerous (malignant). In general, if a tumor is cancerous, it means it’s aggressive, can invade other tissues and potentially spread to other parts of your body. A benign tumor won’t spread to other parts of your body.

Meningiomas are most often found near the top and the outer curve of your brain. They may also form at the base of your skull. Spinal meningiomas are rare.

Meningiomas tend to grow slowly and inward. Often, they’ll have grown quite large before they’re diagnosed. Even benign meningiomas can grow large enough to be life-threatening if they compress and affect nearby areas of your brain.

There are three types of meningioma by grade:

• Grade I or typical: This is a benign meningioma that grows slowly. These tumors represent approximately 80% of cases.
• Grade II or atypical: This is a noncancerous meningioma that grows more quickly and can be more resistant to treatment. These tumors represent approximately 17% of cases.
• Grade III or anaplastic: This is a malignant (cancerous) meningioma that grows and spreads quickly. These tumors represent approximately 1.7% of cases.

There are several different types of meningiomas based on their location and tissue type. Some location examples include:

• Convexity meningiomas, which grow on the surface of your brain and can exert pressure on your brain as they grow.
• Intraventricular meningiomas, which grow within the ventricles of your brain. Your ventricles carry cerebrospinal fluid (CSF).
• Olfactory groove meningiomas are located between your brain and nose at the base of your skull. They grow near your olfactory nerve, which is responsible for your sense of smell.
• Sphenoid wing meningiomas, which form along a ridge of bone behind your eyes.

There are also 15 variations of meningiomas according to their cell type as viewed under a microscope.

Is meningioma considered cancer?

In most cases, meningiomas are benign (noncancerous), but they can sometimes be cancerous (malignant). Even if a meningioma is benign, if it grows large enough, it can press on important nerves and structures of your brain, which can cause harm and even be life-threatening.

Who does meningioma affect?

Meningiomas much more commonly affect adults than children, although children can still develop them. The average age at diagnosis is 66 years. Black people tend to have higher rates of meningioma than other ethnic groups in the United States.

People assigned female at birth (AFAB) are more likely to have a meningioma than people assigned male at birth (AMAB). This is likely due to hormonal factors that contribute to the development of meningiomas.