Ependymoma

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Ependymoma is a neuropathology tumour.

General

  • Called the forgotten glial tumour.

Epidemiology:[1]

  • Usual site:
    • Adults: usu. spinal cord.
    • Children: usu. posterior fossa.
  • May be assoc. with neurofibromatosis 2.

Comes in two main flavours:

  1. Ependymoma (not otherwise specified).
  2. Myxopapillary ependymoma.
    • Classically at filum terminale.

Other flavours:[2]

  • Papillary ependymoma.
  • Clear cell ependymoma.

Microscopic

Classic ependymoma

Features:

  • Cells have a "tadpole-like" morphology.
    • May also be described as ice cream cone-shaped.[3]
  • Rosettes = circular nuclear free zones/cells arranged in a pseudoglandular fashion; comes in two flavours in ependymoma:
    • Perivascular pseudorosettes = (tumour) cells arranged around a blood vessel; nuclei of cells distant from the blood vessel, i.e. rim of cytoplasm (from tumour cells) surround blood vessel (nucleus-free zone); more common than ependymal rosette... but less specific.
    • Ependymal rosette (AKA true ependymal rosette) = rosette has an empty space at the centre - key feature.
  • Nuclear features monotonous, i.e. "boring".[4]
    • There is little variation in size, shape and staining.

DDx (classic ependymoma):

Images

www:

Myxopapillary ependymoma

Features:

  • Perivascular pseudorosettes:
    • Myxoid material surround blood vessels.
      • Myxoid material surrounded by tumour cells.

Images:

Grading

Easy:

  • Subependymoma = WHO grade I.
  • Myxopapillary ependymoma = WHO grade I.

Not-so-easy:

  • Classic ependymoma = WHO grade II.
  • Anaplastic ependymoma = WHO grade III.

Grade II vs. Grade III:

  • Cellular density.
  • Mitoses.
  • Necrosis.
  • Microvascular proliferation.

Notes:

  • Many tumours fall between grade II and grade III. These are called "indeterminate" by many.

IHC

  • Reticulin.
  • GFAP.
  • MIB1.

See also

References

  1. Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1334. ISBN 978-1416031215.
  2. URL: http://emedicine.medscape.com/article/1744030-overview. Accessed on: 17 January 2012.
  3. http://www.pathology.vcu.edu/WirSelfInst/tumor-2.html
  4. MUN. 6 Oct 2009.