Diagnosing Ependymoma

Ependymomas are rare tumors that can develop in the brain or spine. Symptoms vary widely depending on the location of the tumor. The diagnosis can be made with a combination of imaging, analysis of the tumor specimen under a microscope, and molecular testing. Read on to learn more about the different types of ependymoma and how an ependymoma is diagnosed.

According to the 2021 World Health Organization (WHO) classification system, ependymomas are now classified based on location, molecular features, and microscopic appearance. Each ependymoma type may be associated with one or more possible “grades” (Grade 1 to 3). These grades describe the extent of cellular abnormality observed under the microscope, with higher grade tumors being more abnormal and associated with worse prognoses.

Supratentorial ependymomas are found in the brain. Symptoms may include headache, nausea, vomiting, seizures, or other neurological deficits depending on the location of the tumor. Most cases of supratentorial ependymoma are diagnosed in younger children and adolescents. This type of tumor can be assigned a Grade 2 or 3. Subtypes of supratentorial ependymoma are based on molecular alterations and include:

• ZFTA Fusion-Positive Supratentorial Ependymoma: This subtype accounts for most supratentorial ependymomas. Prognosis is typically worse than other supratentorial ependymoma subtypes.
• YAP1 Fusion-Positive Supratentorial Ependymoma: This subtype is rare and often features a large tumor by the time the diagnosis is made. Prognosis is typically better than other supratentorial ependymoma subtypes.

Posterior fossa ependymomas are located around the base of the skull near the brainstem. They may occur in a cavity within the brain called the fourth ventricle. Symptoms can include headache, nausea and vomiting, and lethargy. Posterior fossa ependymomas occur more frequently in children and can be assigned a Grade 2 or 3.

Grading for posterior fossa ependymomas does not have a strong relationship with overall survival rates. Rather, total surgical resection is more consistently associated with longer survival rates than a lower tumor grade. Subtypes of posterior fossa ependymomas are based on molecular alterations and include:

• Posterior Fossa Group A Ependymoma: This subtype mostly occurs in infants and young children. Prognosis is worse than posterior fossa group B ependymomas.
• Posterior Fossa Group B Ependymoma: This subtype occurs in adults and is more common in adolescents than younger infants and children. Incomplete surgical resection, or removal, is associated with poor prognosis. 

Spinal ependymomas occur along the spinal canal and can affect the neck, mid-back, or lower back. Symptoms can include neck or back pain, weakness, or sensory changes such as numbness or tingling. The median age at diagnosis ranges from 25 to 45 years old. Spinal ependymomas can be assigned a Grade 2 or 3. Subtypes are based on molecular alterations and include:

• Spinal Ependymoma MYCN-Amplified: This is a rare subtype that occurs more commonly in the neck or mid-back. Most of these tumors have high-grade features but have not yet been assigned a WHO grade. This is an aggressive tumor that often spreads to other tissues and is associated with worse outcomes than other spinal ependymoma subtypes. 

Myxopapillary ependymomas are found at the low back. Symptoms can include low back pain, pain that radiates down the legs, urinary or fecal incontinence, and weakness or sensory abnormalities in the legs. Overall, survival rates are relatively positive with more than 90% of patients alive at 10 years. However, many may require repeat interventions because of treatment resistance.

Although myxopapillary ependymomas are a type of cancer, they are low grade (Grade 2) and generally associated with long survival times.

Subependymomas are benign growths often located within the cavities of the brain called the ventricles. Most do not produce symptoms and are found incidentally when imaging the brain for an unrelated reason. Outcomes are excellent, and recurrence after surgery is rare.

Older ependymoma classifications such as “anaplastic ependymoma” are part of the older classification system. Anaplastic ependymoma refers to an aggressive Grade 3 ependymoma subtype associated with rapid growth and spread. 

Ependymomas are diagnosed by a combination of imaging tests such as magnetic resonance imaging (MRI) or computed tomography (CT) scans, and tissue biopsy.

• Imaging: Spinal ependymoma MRI or CT scans can help to determine the location and size of the tumor as well as its relationship to surrounding structures. Ependymomas appear as well-defined, contrast-enhancing masses on MRI and may show evidence of cystic change or hemorrhage.
• Biopsy: Tissue analysis can confirm the diagnosis of ependymoma and classify the type of ependymoma based on the appearance of cells under a microscope and the results of other molecular tests. This can help to predict prognosis and outcomes.

For healthcare professionals, an International Classification of Diseases (ICD)-10 code is associated with the ependymoma diagnosis and can help to provide a common language for providers, researchers, and statisticians to communicate about a condition and monitor trends in incidence and prevalence. For example, the ICD-10 code for a spinal ependymoma is C72. This refers to a malignant neoplasm of the spinal cord, cranial nerves, and other parts of the central nervous system.

• Ependymomas are classified based on location, molecular features, and microscopic appearance. Each ependymoma type may be associated with one or more possible “grades” (Grade 1 to 3).
• Supratentorial ependymomas are found in the brain; posterior fossa ependymomas are located around the base of the skull near the brainstem; spinal ependymomas occur along the spinal canal and can affect the neck, mid-back, or lower back
• Ependymomas are diagnosed by a combination of imaging tests and tissue biopsy

• Collaborative Ependymoma Research Network (CERN)
• American Brain Tumor Association (ABTA): Ependymoma
• The Childhood Brain Tumor Foundation 
• Pediatric Brain Tumor Foundation