Ependymomas represent a relatively broad group of glial tumors most often arising from the lining of the ventricles of the brain or the central canal of the spinal cord. They account for ~5% of all neuroepithelial neoplasms, ~10% of all pediatric brain tumors and up to 33% of brain tumors occurring in those less than 3 years of age.

Ependymal tumors can occur anywhere within the neuraxis, but distribution and molecular characteristics are fairly site-dependent, divided into three groups depending on the anatomical compartment in which they are found ^11,13,15:

posterior fossa (60%)
supratentorial (30%)
spinal cord (10%)

In addition to subependymomas, that can be encountered in all three compartments, DNA-methylation profiling divides ependymomas on the basis of their molecular characteristics and their location as differing in epidemiology and prognosis. As such, location forms the basis of the current (2021) WHO classification ^11,13:

posterior fossa
- posterior fossa ependymoma - NEC or NOS
  - posterior fossa group A (PFA) ependymoma
  - posterior fossa group B (PFB) ependymoma
supratentorial compartment
- supratentorial ependymoma - NEC or NOS
  - supratentorial ependymoma, ZFTA fusion-positive
  - supratentorial ependymoma, YAP1 fusion-positive
spinal cord/canal
- spinal ependymoma - NEC or NOS
  - spinal ependymoma, MYCN-amplified
- myxopapillary ependymoma

Quiz questions

References

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