Ependymoma

Ependymoma is a type of tumor that forms in the brain or spinal cord, developing from cells that line the fluid-filled spaces in the central nervous system. While some ependymomas grow slowly and are considered noncancerous, others grow more quickly and are cancerous, requiring a combination of treatments including surgery, radiation, and sometimes chemotherapy.

Table of contents

• What Is Ependymoma?
• Where Ependymomas Form
• Types and Grades
• Causes and Risk Factors
• Who Is Affected
• Symptoms
• Diagnosis
• Treatment
• How Ependymomas Spread
• Recurrence

What Is Ependymoma?

Ependymoma is a growth of cells that forms in the brain or spinal cord. The cells form a mass called a tumor, which is an abnormal growth of tissue. Ependymomas begin in the ependymal cells, which are specialized cells that line the passageways that carry cerebrospinal fluid. This fluid surrounds and protects the brain and spinal cord^[1].

Ependymomas are primary tumors, which means they form directly in your brain or spinal cord rather than spreading there from somewhere else in your body^[2]. They are a type of glioma, a tumor that starts in support cells (glial cells) of the brain^[8].

Ependymal cells are one of three types of glial cells that support the central nervous system. These cells help create cerebrospinal fluid and line the fluid-filled spaces in the brain called ventricles, as well as the central canal of the spinal cord^[3].

Where Ependymomas Form

Ependymomas can form anywhere in the central nervous system. They often occur near the ventricles in the brain and the central canal of the spinal cord^[3]. In children, about 65% to 75% of ependymomas arise in the lower back part of the brain, called the posterior fossa, around the fourth ventricle^[6]. Less commonly, they appear in the upper part of the brain, known as the supratentorial region^[15].

In adults, most ependymomas start in the ependymal cells that line the spinal cord^[7]. They are more likely to form in the spinal cord than in the brain in adult patients^[1]. On rare occasions, ependymomas can form outside the central nervous system, such as in the ovaries, although this is very uncommon^[3].

Types and Grades

Ependymomas are grouped into grades based on how quickly they grow and how the cells look under a microscope. Healthcare providers grade ependymomas on a scale from 1 to 3, with Grade 1 tumors growing the slowest and Grade 3 growing the fastest^[2].

Grade 1 ependymomas are low-grade tumors that grow slowly. This category includes subependymomas, which are slow-growing tumors that usually appear near a ventricle in the brain or in the spine. They are more common in adults than children and often do not cause symptoms^[3].

Grade 2 ependymomas are also low-grade tumors, but they are more likely to return after treatment than Grade 1 tumors, especially if they cannot be completely removed during surgery. This grade includes myxopapillary ependymomas, which are usually slow-growing and found in the lower part of the spinal cord, and conventional ependymomas, which can occur in either the brain or spine^[3].

Grade 3 ependymomas are malignant, meaning they are cancerous. These are fast-growing tumors that occur most often in the brain but can also appear in the spine. Anaplastic ependymomas are Grade 3 tumors that usually form near the base of the brain, grow quickly, and often spread to other parts of the brain. They are the most likely to return after treatment^[2].

According to the 2021 World Health Organization classification, ependymomas are also classified based on anatomical location and molecular features. The main subtypes include supratentorial ependymoma, posterior fossa ependymoma (divided into groups A and B), spinal ependymoma, myxopapillary ependymoma, and subependymoma^[3].

Causes and Risk Factors

The cause of ependymomas is not known. Most cases occur sporadically, with no confirmed cause^[5]. Researchers do not yet know what causes these tumors to form or what specific risk factors increase the likelihood of developing them^[8].

However, certain inherited conditions have been linked to ependymoma. People with a genetic disorder called neurofibromatosis type 2 have a higher risk of developing an ependymoma^[3]. Some studies have found that people who carry genetic variations that cause neurofibromatosis type 2 may be more likely to develop these tumors, but experts are still studying this possible connection^[2].

Ependymomas may happen by mistake when ependymal cells in the brain divide and replicate. Some genetic variations may cause them, but the exact mechanism is still being researched^[2].

Who Is Affected

Ependymomas affect all age groups, with a higher frequency in children^[6]. They are the third most common brain tumor in pediatric patients^[6], and the sixth most common brain tumor in children overall^[2].

Ependymomas comprise approximately 9% of all childhood brain and spinal cord tumors, representing about 200 to 250 cases per year in the United States^[4]. In children, most ependymomas are diagnosed in those ages 8 and younger^[5].

In adults, ependymomas are less common. Less than 2% of central nervous system tumors in adults are ependymoma, with approximately 1,100 adults diagnosed per year in the United States^[4]. Adults with ependymomas are often diagnosed in their 30s or 40s, with a median age of 44 years^[5][6].

Symptoms

Symptoms of ependymoma depend on where the tumor is located and how large it is. The tumor causes symptoms by pressing on nearby structures and, in some cases, by blocking the normal flow of cerebrospinal fluid^[13].

People with an ependymoma in the brain may experience headaches, nausea and vomiting, blurry vision, confusion, irritability, seizures, dizziness, weakness, fatigue, loss of appetite, trouble concentrating, mood changes, personality changes, loss of coordination, balance problems, and difficulty walking^[1][2][5].

Sometimes, an ependymoma blocks the flow of cerebrospinal fluid, leading to a condition called hydrocephalus. This causes fluid to build up in the ventricles, putting pressure on the brain within the skull. This can lead to increased pressure inside the head, causing additional symptoms^[5][8].

If the ependymoma is located in the spinal cord, symptoms can include back pain, neck pain, neck stiffness, numbness and weakness in the arms, legs, or trunk, muscle weakness, bladder and bowel problems, and loss of control over urination or bowel movements^[1][3][5].

Babies and very young children cannot express that they are feeling pain or other symptoms. Parents might notice a larger-than-usual head, sleeplessness, unusual irritability or fussiness, and vomiting or spitting up more than usual^[2].

Diagnosis

A healthcare provider will diagnose an ependymoma by learning about a patient’s medical history, performing a physical exam, and offering diagnostic tests^[2]. Doctors will ask how long symptoms have occurred and whether there is a family history of cancer or brain tumors. They also perform a neurological exam to check vision, hearing, balance, coordination, strength, and reflexes. Problems in one or more of these areas may provide clues about which part of the brain or spinal cord could be affected by a tumor^[9].

Imaging tests are used to create pictures of the body and show the location and size of the tumor. Magnetic resonance imaging (MRI) is often used to diagnose brain tumors and may be used along with specialized MRI imaging. Because ependymomas can happen in both the brain and the spinal cord, imaging tests may be used to create pictures of both areas^[9]. Ependymomas usually appear as one or more well-defined masses that often brighten with contrast on an MRI scan^[3].

A CT scan (computed tomography scan) is another imaging exam that allows doctors to see tumors, growths, or abnormalities in the brain or spinal cord^[5].

A lumbar puncture, also called a spinal tap, is a procedure in which a needle is inserted into the spinal canal to remove cerebrospinal fluid for analysis. This test can confirm the presence of an ependymoma and check whether tumor cells have spread through the cerebrospinal fluid^[5][9].

A biopsy is a procedure in which doctors remove a small amount of the tumor to determine if the cells are cancerous. To get an accurate diagnosis, a piece of tumor tissue will be removed during surgery, if possible. A neuropathologist, a specialist who studies diseases of the nervous system, should then review the tumor tissue under a microscope^[3][5]. If possible, doctors may opt to remove the entire tumor rather than just a portion for biopsy^[5].

Treatment

Surgery is the primary treatment for ependymoma. The goal of surgery is to remove as much of the tumor as possible without causing additional problems. A highly specialized doctor called a neurosurgeon performs the surgery. Sometimes the ependymoma is located near sensitive brain or spinal tissue, making complete removal too risky. If the entire tumor is removed, additional treatments may not be needed^[9][4].

Radiation therapy uses powerful X-rays or other forms of energy to destroy tumor cells. Patients might need radiation before or after surgery, especially for tumors that are growing quickly or for tumors that cannot be removed completely with surgery^[1][2]. Radiation therapy may be given to the whole brain and spinal cord if the ependymoma has spread to the cerebrospinal fluid, or it may be given just to the area of the tumor if there are no tumor cells found in the fluid^[7].

Chemotherapy is medication that kills cancer cells. Chemotherapy is usually only needed if the tumor has spread to other areas of the body, which is very rare with ependymomas^[2]. Additional treatments such as targeted therapy or immunotherapy may also be recommended in some cases^[1].

The best outcomes occur when all or most of the tumor is removed during surgery^[5]. Treatment effectiveness depends on the tumor’s location within the brain or spinal cord, the grade of the tumor, and whether it can be completely removed^[5].

How Ependymomas Spread

Ependymomas rarely spread outside the central nervous system. However, they can spread to other areas within the brain or spinal cord through cerebrospinal fluid^[3]. These tumors can spread when the cerebrospinal fluid carries ependymoma cells to other places in the brain or spinal cord^[8].

In general, ependymal tumors tend not to invade nearby tissue but instead displace it as they grow. This characteristic makes surgical removal of many of these tumors possible^[13]. About 10 to 15% of ependymomas spread within the central nervous system^[13]. It is very rare for an ependymoma to spread to other parts of the body outside the central nervous system^[13].

Recurrence

Ependymomas can return, or recur, after initial treatment. Grade 2 ependymomas are more likely to recur than Grade 1 tumors, especially if they cannot be completely removed during surgery^[3]. Anaplastic ependymomas, which are Grade 3 tumors, are the most likely to regrow after treatment^[2].

Ependymoma recurrences can occur at the site of the original tumor (locally) or at other locations in the central nervous system (distantly)^[4]. When ependymomas return, patients may need additional surgeries and treatments^[4].