What Is An Ependymoma?

Ependymoma is a rare tumor that can occur in the brain or spine. Approximately 1000 people in the United States are diagnosed with ependymoma annually. Based on its appearance under a microscope, location, and molecular features, an ependymoma can be classified into different types and grades, each associated with a different survival outlook. Continue reading to learn more about ependymoma, where it begins, its different types and grades, how common the condition is, and more.

Ependymoma is a tumor of the central nervous system (CNS) that can begin in the brain or spinal cord. It arises from ependymal cells that line the ventricles (cavities) of the brain and central canal of the spinal cord. Ependymal cells help to produce the clear cerebrospinal fluid (CSF) that surrounds the brain and spinal cord.

Like tumors in general, ependymomas develop when healthy cells grow out of control, forming a mass. Ependymomas typically manifest as soft, grayish, or red tissue containing cysts or mineral calcifications. The tumor can occasionally spread within the central nervous system by traveling through cerebrospinal fluid, but it rarely goes outside of the brain or spine.

Patients with ependymoma may experience varying symptoms depending on the tumor's location. As the tumor grows, it can block the flow of cerebrospinal fluid and cause pressure buildup. As a result, patients with brain ependymoma may experience headaches, nausea, and seizures, whereas those with spine ependymoma often complain of back pain, urinary or bowel problems, and numbness in the legs, arms, or trunk

Ependymoma is relatively rare, affecting about 4 per 100,000 people. Both children and adults can be affected. Ependymoma occur more often in the brain in children and the spine in adults. In the spine, ependymomas are the most common primary intramedullary spinal cord glioma below the mid-back area. The average age of diagnosis for ependymomas in the brain is 5 years old. Meanwhile, the average age of diagnosis for ependymomas in the spinal cord is 40 years old.

Ependymomas can be categorized into different types based on its location, molecular features, and appearance under a microscope (histology) as follows:

• Location: Supratentorial (upper part of the brain), posterior fossa (base of the skull near the back of the head), and spine.
• Molecular features: The presence of genetic alterations in the tumor.
• Histology: Characteristics under a microscope including the density of tumor cells (cellularity), variability in cell size and shape (pleomorphism), growth of blood vessels (vascular proliferation), and presence of actively dividing cells (mitotic count).

Certain ependymoma types can be assigned a World Health Organization (WHO) grade. The grade provides information on how abnormal the tumor cells appear and a sense of its growth rate. Grade 1 is slow-growing and least likely to spread, Grade 3 is fast-growing and more likely to spread. Grade 2 tumors exhibit characteristics in between those of Grades 1 and 3.

In 2021, new WHO classification guidelines for ependymoma were released. You might hear these ependymoma types during a discussion with your doctor. However, the discussion will likely focus more on the implication of your diagnosis rather than the exact classification. Ependymomas with mixed features may be more difficult to categorize.

• Supratentorial ependymoma, ZFTA or YAP1 fusion-positive (Grade 2 or 3)
• Posterior fossa ependymoma, group A or B (Grade 2 or 3)
• Spinal ependymoma, MYCN-amplified (Grade 2 or 3)
• Myxopapillary ependymoma (Grade 2)
• Subependymoma (Grade 1)

Whether an ependymoma is benign or malignant depends on its growth rate and tendency to spread. Grade 1 tumors such as subependymomas are benign, meaning that they typically grow very slowly and do not spread. Treatment options such as surgery are often curative. Grade 3 tumors such as a Grade 3 spinal ependymoma are malignant. This means that they have rapid growth rates and are more likely to spread to other parts of the body. These tumors tend to recur even after treatment. 

Survival and outcomes depend on the type of tumor and the treatment administered. In general, the ependymoma prognosis is worse with high-grade tumors (e.g., Grade 3) because of their tendency to recur and spread. If surgery is undertaken, safe and complete removal is the goal.

•  Ependymoma is a rare tumor that can occur in the brain or spine and affects approximately 13,000 people in the United States.
•  Ependymomas occur more often in the brain in children and in the spine in adults.
•  Ependymomas can be classified based on anatomic site, molecular features, and appearance under the microscope.