Ependymoma
Epidemiology:
- Children and young
adults
Common sites:
- Paraventricular
- 4th
ventricle in children
- Cortical (supratentorial)
- Spinal cord
(adults)
- myxopapillary ependymoma:
- cauda equine (83% of all cauda equina tumours)
Gross features:
- sharply demarcated
- calcifications
- cyst formation
Histologic features:
- well circumscribed
- nuclear free zones
- perivascular (pseudorosettes)
(all glial cells do this)
- “rosettes” –
lumen with cilia and microvilli lined by oval nuclei with a basal
polarization (more specific)
- myxopapillary ependymoma
(grade 1 by definition) (common exam question!):
- grading:
- I – myxopapillary ependymoma
- II – few mitoses
- III – anaplastic,
numerous mitoses, +/- endothelial proliferation
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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GFAP
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Most
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S100
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100%
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EMA (rings AND dots)
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CD99 (rings AND dots)
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Molecular features:
- EM – intracytoplasmic lumen with tangles of microvilli
- Long zipper-like
intercellular junctions
Other features:
- May cause obstructive
hydrocephalus
- Spinal tumours have better prognosis
- Myxopapillary ependymoma
(13%):
- Good prognosis
(grade I always)
References: