• A high power view of a pseudorosettes in an ependymoma.
• The neoplastic cells palisade around a capillary (arrow).
• These tumors can also form true rosette, that is palisading of nuclei about an empty space with a membrane bounding the lumen.
• Arises predominantly in the cerebellum or brainstem but
also in the cerebral hemispheres and spinal cord when
oncogenes become activated and tumor suppressor genes
•Loss of chromosome 22 is the most
comman gene abnormality seen.
•The etiology of these changes are unknown.
•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.
•Ependymomas account for approximately 6% of CNS tumors.
•They cause symptoms related to where they arise.
•Tumors arising in the cerebellum will cause
ataxia and headache as well as increased intracranial
pressure from blockade of the fourth ventricle.
• Tumors arising from the brainstem may cause
cranial nerve signs and pyramidal tract signs, as well as
headache and increased intracranial pressure.
malignant varieties that metastasize to the CSF pathway
may also cause nerve root signs.
•For more information on prognosis and treatment, consult NCI web site.
|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 Micro Description|
•Microscopically the ependymoma looks like an inverted
•It forms rosettes - a circle of cells
about an imaginary space or pseudorosettes -a circle of
cells sending processes down to a capillary.
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.
• 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.