eMedicine Specialties > Pediatrics: General Medicine > Oncology

Ependymoma

Author: Tobey MacDonald, MD, Clinical Director of Neuro-Oncology, Children's Hospital National Medical Center; Associate Professor, Department of Pediatric Hematology-Oncology, George Washington University
Coauthor(s): Roger J Packer, MD, Executive Director, Neuroscience and Behavioral Medicine, Director, Brain Tumor Institute, Children's National Medical Center; Professor of Neurology and Pediatrics, The George Washington University
Contributor Information and Disclosures

Updated: Feb 12, 2009

Introduction

Background

Ependymoma is the third most common brain tumor in children, accounting for approximately 10% of primary CNS neoplasms. It is a neuroepithelial tumor that arises within, or adjacent to, the ependymal lining of the ventricular system or the central canal of the spinal cord. It tends to invade locally, even if histological appearance is benign. Approximately 90% of tumors are intracranial, with as many as 70% occurring in the posterior fossa. With surgery and radiotherapy, the overall 5-year survival rate is approximately 55%; however, survival rates as high as 80% can be achieved. Individual prognosis mostly depends on age and the extent of resection. The role of chemotherapy for infants and patients with postoperative residual disease is currently under investigation.

Pathophysiology

Ependymomas typically arise from the ependymal lining of the ventricular system, most often the floor, roof, or lateral recesses of the fourth ventricle. The most recent evidence suggests that radial glia cells are the stem cells of origin for this disease. Approximately one third of ependymomas are supratentorial, arising from the surface of the lateral or third ventricles; however, they may be entirely extraventricular. They may also occur in the central canal of the spinal cord and in the filum terminale, although the latter site is uncommon in children.

Histologically, ependymoma can be broadly separated into two major subsets, low-grade (cellular) and high-grade (anaplastic). Low-grade ependymoma is well differentiated and lacks mitosis and vascularity. High-grade ependymoma is poorly differentiated and has a high mitotic index, necrosis, calcifications, and endothelial proliferation. Both histological subtypes are locally invasive into adjacent brain. Those in the posterior fossa frequently infiltrate the brain stem, and as many as one third may project through the foramina to involve the medulla and upper spinal cord. Spread via cerebrospinal fluid (CSF) throughout the subarachnoid space is reported, primarily with the higher-grade tumors. Extraneural metastases to liver, lung, or bone are rare. Myxopapillary ependymomas are considered a distinct variant of ependymoma primarily occurring in the region of the cauda equina.

Frequency

United States

Approximately 140 new cases are reported annually in children younger than 15 years. Ependymoma represents the third most common brain tumor in children, following astrocytoma and medulloblastoma.

International

In the United Kingdom, an estimated 30-35 new pediatric cases are diagnosed annually. More than 300 new pediatric cases per year are reported in Europe.

Mortality/Morbidity

Overall survival rate is approximately 55%. Age and the extent of tumor resection are significant independent predictors of outcome. Five-year survival rate is 25% for infants younger than 1 year, 46% for children aged 1-4 years, and greater than 70% for those older than 5 years. Most patients (as high as 85%) achieve a gross total resection prior to additional therapy because of improved neurosurgical techniques. For those patients in whom complete tumor resection can be achieved, survival rates of 60-80% have been reported following local radiation. In those with partial resection or biopsy only, fewer than 30% respond to currently available best nonsurgical therapy, regardless of age or tumor histology.

Direct distortion and destruction of normal brain tissue by tumor, as well as increased intracranial pressure and surgical trauma, may cause some degree of irreversible neurologic impairment. Also, the volume and location of radiotherapy necessary to treat the tumor may result in cognitive impairment. The expanded use of conformal radiotherapy for localized disease has helped to ameliorate some of these effects.

Radiotherapy to the hypothalamic-pituitary axis may result in deficits of growth hormone, thyroid hormone, gonadotropin, and adrenocorticotropic hormone.

Race

No specific race is predisposed to ependymoma.

Sex

The male-to-female ratio is approximately 1:1.

Age

The mean age at diagnosis is 5-6 years, and 25-40% of cases occur in children younger than 3 years. Spinal cord ependymoma rarely occurs in children younger than 12 years.

Clinical

History

• Initial symptoms of ependymoma are usually nonspecific, nonlocalizing, and related to increased intracranial pressure (ICP).
  • The classic triad of raised ICP consists of morning headaches, vomiting, and lethargy. The classic headache of increased ICP is pain present upon rising, relieved by vomiting, and gradually decreasing during the day.
  • School-aged children more commonly complain of vague, intermittent headaches and fatigue. They may demonstrate declining academic performance and exhibit personality changes.
  • Infants may present with irritability, anorexia, and developmental delay or regression.
• Supratentorial lesions may be associated with seizures and focal cerebral deficits.
• Posterior fossa tumors may lead to cerebellar dysfunction, resulting in balance and gait disturbances that frequently are associated with vomiting and lower cranial nerve findings such as diplopia, facial weakness, tinnitus, vertigo, and hearing loss.
• Spinal cord tumors may cause symptoms of spinal cord compression, such as back pain and loss of bladder and/or bowel control.

Physical

• Increased ICP findings
  • A funduscopic examination reveals papilledema. Infants may have only optic pallor.
  • Palsy of cranial nerve VI, resulting in the inability to abduct one or both eyes, is common.
  • Infants may demonstrate the setting sun sign, observed as an impaired upgaze and a forced downward deviation of both eyes. Measurement of head circumference in infants with open cranial sutures may reveal macrocephaly.
• Localized deficits in truncal steadiness, upper extremity coordination, and gait may be observed with posterior fossa tumors.
• The inability to deviate both eyes conjugatively (gaze palsy), or the inability to adduct one eye on attempted lateral gaze may be seen with tumor invasion into the brainstem.
• Extension of posterior fossa tumors through the foramina of Luschka may impair function of the lower cranial nerves (primarily VI, VII, VIII, IX, and X).

Causes

• Epidemiological studies investigating parental occupational exposures, environmental exposures, and maternal nutritional intake have failed to identify linkages with any of the childhood brain tumors.
• DNA sequences similar to SV40 virus and the virus-encoded large T-antigen have been found in several ependymomas, but no conclusions regarding causation have been determined. SV40 and related polyoma viruses can induce ependymoma in monkeys and other mammalian species.

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