Malignant Meningioma

Malignant meningioma is a rare and aggressive form of brain tumor that grows quickly and requires prompt treatment. Though most meningiomas are noncancerous, these cancerous tumors demand specialized care and close monitoring.

Table of contents

• What Is Malignant Meningioma?
• Where Malignant Meningiomas Form
• Grades of Meningiomas
• Symptoms
• Causes and Risk Factors
• How Doctors Diagnose Malignant Meningioma
• Treatment Options
• Outlook and Survival

What Is Malignant Meningioma?

A meningioma is a tumor that grows from the layers of tissue that cover and protect the brain and spinal cord, called the meninges. The meninges are three protective layers: the tough outer layer called the dura mater, the web-like middle layer called the arachnoid, and the delicate inner layer called the pia mater.^[1][2]

Meningiomas are the most common type of primary brain tumor. While most of these tumors are noncancerous and grow slowly, malignant meningiomas are cancerous and grow much faster.^[1][3]

• Brain
• Spinal cord
• Meninges (protective tissue layers)

Where Malignant Meningiomas Form

Meningiomas form along the dura mater, which is the outermost layer of tissue that covers and protects the brain and spinal cord. These tumors arise from cells in the meninges and tend to occur along the surface of the brain.^[3]

These tumors are most often found near the top and outer curve of the brain. They may also form at the base of the skull. Tumors that form around the spine are possible but rare.^[1][4]

Grades of Meningiomas

Meningiomas are grouped into three grades based on how the tumor cells look under a microscope and how fast they grow. A neuropathologist, a doctor who specializes in examining tumor tissue, reviews the tumor to determine its grade.^[3]

Grade 1 (typical) meningiomas are noncancerous tumors that grow slowly. These are the most common type.^[1][3]

Grade 2 (atypical) meningiomas are noncancerous but grow more quickly than Grade 1 tumors. They have a higher chance of coming back after treatment. Grade 2 meningioma types include chordoid and clear cell meningiomas.^[1][3]

Grade 3 (anaplastic) meningiomas are malignant, meaning they are cancerous. These are fast-growing tumors that spread quickly. Grade 3 types include papillary and rhabdoid meningiomas. These are rare tumors.^[1][3]

Grade 3 meningiomas have irregular cells and are likely to invade the brain or spread to other organs in the body. They can spread to other areas of the central nervous system (the brain and spinal cord) through cerebrospinal fluid, the liquid that circulates throughout the brain and spine.^[3]

Symptoms

Because meningiomas typically grow slowly, they may not cause noticeable symptoms until they grow large enough to push on important structures around them. Symptoms can vary depending on which part of the brain the tumor affects.^[1][2]

The symptoms of a meningioma most often begin slowly and may be hard to notice at first. Common symptoms may include:^[1][2][3]

• Headaches that are worse in the morning
• Vision changes such as seeing double or blurriness
• Hearing loss or ringing in the ears
• Loss of smell
• Memory problems
• Confusion
• Muscle weakness
• Seizures

Causes and Risk Factors

The cause of most meningiomas is not known. However, most tumors happen because of a chromosomal deletion, which is a genetic change where part of a chromosome is missing. These changes happen randomly in most cases.^[1][3]

Exposure to radiation, especially in childhood, can increase a person’s risk of developing a meningioma. People who have a genetic condition called Neurofibromatosis type 2 are also at increased risk.^[1][3]

You may also inherit genetic mutations as part of certain genetic conditions, including:^[1]

• Cowden syndrome
• Li-Fraumeni syndrome
• Multiple endocrine neoplasia type 1
• Von Hippel-Lindau disease

Meningiomas can affect anyone, but you may be more at risk if you:^[1]

• Are over age 65
• Are Black
• Are using hormone replacement therapy or birth control pills
• Had or have breast cancer
• Underwent radiation therapy on your head
• Have a biological relative with meningiomas

Grade 1 meningiomas are more common in females, but grades 2 and 3 occur more often in males. High-grade meningiomas tend to occur in people around 60 years old, and the risk of developing this tumor increases with age.^[1][3]

An estimated 3,360 people are living with high-grade meningiomas in the United States.^[3] Each year, more than 39,000 Americans are diagnosed with meningioma.^[5]

How Doctors Diagnose Malignant Meningioma

To diagnose a meningioma, a healthcare provider will perform a physical and neurological exam. This exam checks your brain and nerve function. The provider will confirm the diagnosis with imaging tests like a CT scan (computed tomography scan) or an MRI (magnetic resonance imaging).^[1][2]

A meningioma can be difficult to diagnose because it grows slowly and doesn’t cause symptoms until it’s bigger. Also, symptoms may resemble normal signs of aging in adults over 65.^[1]

Grade 2 and 3 meningiomas usually appear as an enhancing mass on the outside lining of the brain tissue, which may or may not brighten with contrast dye on an MRI scan.^[3]

To get an accurate diagnosis, a piece of tumor tissue will be removed during surgery, if possible. A neuropathologist will then review the tumor tissue to determine the grade.^[3]

Treatment Options

Treatment for malignant meningioma depends on many factors, including the size and location of the tumor, how fast it is growing, your age, and your overall health.^[2]

Surgery

Surgery to remove the tumor is the most common treatment. The goal is to remove the entire tumor and the membranes from which it originates. Complete removal decreases the risk of the tumor returning. This procedure, called a craniotomy, typically involves removing the tumor through a window-like opening cut into the skull, which is closed after the surgery.^[4][8]

The ability to remove the tumor completely depends on its location, whether it is attached to critical nerves or blood vessels, and the patient’s age.^[4]

Radiation Therapy

Radiation therapy in combination with surgery may be recommended for aggressive meningiomas, especially malignant ones. Fourteen patients (93.3%) in one study received radiotherapy after surgical removal of malignant meningiomas.^[6]

For patients whose tumors come back after initial treatment, radiosurgery may be used. Radiosurgery is a focused form of radiation treatment. In one study, patients who had tumor recurrence were treated with radiosurgery after a second tumor removal or with radiosurgery alone, and no further recurrence was observed during follow-up.^[6]

Emerging Treatment Options

Classical chemotherapy drugs and hormone treatments have shown only limited success in treating meningiomas. However, newer targeted therapies are being studied. Some medications that target blood vessel growth in tumors, such as sunitinib and bevacizumab, have shown promising results in small studies.^[13]

Outlook and Survival

Malignant meningiomas are rare and have a worse outlook than noncancerous meningiomas. About 1 to 3% of meningiomas can transform into malignant tumors, with a 5-year survival rate of 32 to 64%.^[7]

According to one study of malignant meningiomas treated with aggressive surgery and radiation, the 5-year progression-free survival rate was 53.6%. Recurrences were confirmed in 4 patients (26.7%) during follow-up, with a median recurrence time of 35 months.^[6]

Treatment success depends on how much of the tumor can be removed during surgery and the biology of the tumor. Malignant meningiomas have the lowest survival rate compared to other grades. Specific genetic changes found in the tumor also contribute to the likelihood of the tumor coming back after surgery.^[4]

If the tumor is large and untreated, complications may include memory loss, paralysis, personality or behavioral changes, speech difficulty, and vision loss.^[1]