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| Ependymoma |
| Etiology • Arises predominantly in the cerebellum or brainstem but also in the cerebral hemispheres and spinal cord when oncogenes become activated and tumor suppressor genes become deleted. •Loss of chromosome 22 is the most comman gene abnormality seen. •The etiology of these changes are unknown. |
| Pathogenesis •See etiology., |
| Epidemiology •Ependymomas of the cerebellum and brainstem are most common in children under 12. •Those in the cerebral hemispheres are seen in children or adults and those in the spinal cord are seen in adults. |
| General Gross Description •The ependymoma is a grayish, granular sometimes necrotic or hemorrhagic tumor which often arises from the ventricles as an exophytic growth. •It may invade other structures and is circumscribed but not encapsulated. •More malignant varieties may metastasize along CSF pathways. |
| General Microscopic Description •Microscopically the ependymoma looks like an inverted neural tube. •It forms rosettes - a circle of cells about an imaginary space or pseudorosettes -a circle of cells sending processes down to a capillary. •Between rosettes and pseudorosettes are cells with oval pale nuclei and indistinct cytoplasmic borders. •The cells look much like normal ependymal cell with uniform nuclei and epithelial like cytoplasm. |
| Clinical Correlation •Ependymomas account for approximately 6% of CNS tumors. •They cause symptoms related to where they arise. •For instance, tumors arising in the cerebellum will cause ataxia and headache as well as increased intracranial pressure from blockade of the fourth ventricle, whereas, if an ependymoma arises from the brainstem it may cause cranial nerve signs and pyramidal tract signs, as well as headache and increased intracranial pressure. •More malignant varieties that metastasize to the CSF pathway may also cause nerve root signs. •The recurrence rate is about 50% with relatively low 5 year survival rates particularly in very young children. |
| References • Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp. 27-28. • Greenfield's Neuropathology, 6th ed. Graham DI, Lantos PL (ed), New York: Arnold, 1997, pp. 636-645. |
| Ependymoma |
| Synopsis by: M. L. Grunnet M.D. (TX2000M93913)[345] |
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