Meningioma: A Plain-Language Guide

A meningioma is a primary central nervous system tumor. That means it begins in the brain or spinal cord. It has not spread there from somewhere else.

NCI's page on meningioma describes the origin precisely. These tumors form along the dura mater. That is the outermost of the three layers making up the meninges, the covering that protects the brain and spinal cord. They arise from meningeal cells. So they tend to occur along the surface of the brain, rather than deep inside it.

NCI states that meningiomas are the most common type of primary brain tumor overall. NCI's PDQ summary on central nervous system tumors puts numbers on that. Meningiomas and other mesenchymal tumors make up 27% of primary brain tumors. Only anaplastic astrocytomas and glioblastomas rank higher, at 38%.

The second half of NCI's statement matters just as much. Higher grade meningiomas are very rare.

Grading comes from tissue, not from a scan. NCI says an accurate diagnosis needs tumor tissue, removed during surgery where possible. A neuropathologist then reviews it.

Grade 1 meningiomas are the most common. NCI calls them low grade tumors, meaning the cells grow slowly.

Grade 2, called atypical, are mid-grade. NCI describes the practical difference: they have a higher chance of coming back after they have been removed. Named subtypes are chordoid and clear cell meningiomas.

Grade 3, called anaplastic, are malignant and fast-growing. Named subtypes are papillary and rhabdoid meningiomas.

NCI's PDQ summary on CNS tumors describes WHO grade I lesions in general. They have low growth potential. They are frequently discrete. And surgery alone may cure them.

NCI describes three distinct patterns of spread, and they line up with the grades.

Meningiomas can spread to other areas of the central nervous system through cerebrospinal fluid.

Grade 2 meningiomas can invade surrounding tissue, including nearby bone.

Grade 3 meningiomas have irregular cells. NCI says they are likely to invade the brain, or spread to other organs in the body.

That last point is unusual for a brain tumor, and it explains why a grade 3 diagnosis changes both the imaging plan and the treatment plan.

NCI describes the typical appearance of grade 2 and grade 3 meningiomas on MRI. They usually appear as an enhancing mass on the outside lining of the brain tissue, which may or may not brighten with contrast.

That qualification is worth noticing. Contrast behavior is not a reliable way to tell grade, which is another reason the neuropathologist's reading of tissue carries the decision.

Meningiomas sit on the surface and press rather than invade. So symptoms follow the map, not the tumor type. NCI lists what can occur.

• Vision changes
• Loss of hearing or smell
• Confusion
• Seizures
• Headaches that are worse in the morning

The morning headache detail is specific enough to be useful. It reflects pressure inside the skull, which tends to be higher after lying flat overnight.

NCI's demographic picture is unusually clear-cut, and it inverts between grades.

Grade 1 meningiomas are more common in females. Grades 2 and 3 occur more often in males.

High-grade meningiomas are most common in non-Hispanic white people. They tend to occur in people around 60 years old, and risk rises with age.

NCI gives a prevalence figure: an estimated 3,360 people are living with high-grade meningiomas in the United States, as of December 31, 2019.

NCI states plainly that the cause of meningiomas is not known.

It then names two things that raise risk. Exposure to radiation, especially in childhood, can increase a person's risk of developing a meningioma. And people with the genetic condition neurofibromatosis type 2 are at increased risk.

That radiation link is not theoretical. NCI's PDQ summary on late effects of childhood cancer treatment reports meningioma among subsequent neoplasms in childhood cancer survivors, with a 30-year cumulative incidence of 3.1%.

For a malignant meningioma, NCI says the first treatment is surgery, if possible.

It gives the goal in two parts. Obtain tissue to determine the tumor type. And remove as much tumor as possible without causing more symptoms.

That second clause is the whole tension of meningioma surgery. Because these tumors sit against the brain surface and often near nerves and vessels, the amount removed is limited by what can be removed safely.

Most people with atypical and anaplastic meningiomas get more treatment after surgery. NCI names radiation, chemotherapy, or clinical trials. It says trials test new chemotherapy, targeted therapy, or immunotherapy drugs.

Decisions are made by the care team based on four things NCI lists: the patient's age, how much tumor remains after surgery, the tumor type, and the tumor location.

NCI publishes one number here. The relative five-year survival rate for high-grade meningioma is 63.5 percent.

That figure covers grades 2 and 3 only, which NCI has already described as very rare compared with grade 1. It is not the number for the common form of this tumor.

NCI also lists what shifts prognosis away from any average. Tumor grade. Location. Tumor type. Extent of spread. Genetic findings. The person's age. And how much tumor remains after surgery, where surgery is possible. It adds response to treatment as well.

Two things NCI does not publish for meningioma are worth naming. There is no surveillance imaging schedule on this page, and no separate survival figure for grade 1 disease. Both are questions for the treating team.

The wider category is described in brain tumors, with the range of diagnoses in brain tumor types. The symptom question people most often arrive with is handled in is a headache a sign of a brain tumor.

• NCI: meningioma diagnosis and treatment
• NCI PDQ: CNS tumors, HP version
• NCI PDQ: late effects, HP version