Difference between revisions of "Pilocytic astrocytoma"

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#redirect [[Neuropathology_tumours#Pilocytic_astrocytoma]]
Pilocytic_astrocytoma]]
 
==General==
*Low-grade [[astrocytoma]] - ''WHO Grade I'' by definition.
*Classically in the cerebellum in children; most common glioma in children.<ref name=Ref_PSNP82>{{Ref PSNP|82}}</ref>
*The ''optic glioma'' associated with neurofibromatosis 1.
 
==Gross==
Features:<ref name=Ref_PSNP82>{{Ref PSNP|82}}</ref>
*Usually well-circumscribed.
*Cystic ''or'' solid.
*Do '''not''' smear. (Ref. ?)
 
==Microscopic==
Features:<ref name=Ref_PSNP82-4>{{Ref PSNP|82-4}}</ref>
*Classically biphasic (though either may be absent):
*#Fibrillar.
*#Microcystic/loose.
*Hair-like fibres ~ 1 micrometer; ''pilo-'' = hair.<ref>URL: [http://dictionary.reference.com/browse/pilo- http://dictionary.reference.com/browse/pilo-]. Accessed on: 24 November 2010.</ref>
**Best seen on smear or with GFAP [[IHC]].
*Rosenthal fibres - '''key feature'''.
**May be rare.  Not pathognomonic (see below).
*Eosinophilic granular bodies.
*Low cellularity - when compared to medulloblastoma and ependymoma.
 
Notes:
*+/-Microvascular proliferation.
*+/-Focal necrosis.
**Necrosis with pseudopalisading more likely glioblastoma.
*+/-Mitoses - not significant in the context of the Dx.
 
DDx (of Rosenthal fibers):<ref>MUN. 9 Mar 2009.</ref>
*Chronic reactive gliosis.
*Subependymoma.
*Ganglioma.
*Alexander's disease (rare leukodystrophy).
 
DDx of pilocystic astrocytoma (brief):
*Piloid gliosis.
*Oligodendroglioma.
*Glioblastoma (uncommon - but important).
 
===Images===
*Smears:
**[http://commons.wikimedia.org/wiki/File:Pilocytic_astrocytoma_-_smear_-_very_high_mag.jpg Bipolar cells with hair-like processes - smear - very high mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Pilocytic_Micro.jpg EGBs - smear (WC/AFIP)].
**[http://commons.wikimedia.org/wiki/File:Rosenthal_fibers.jpg Rosenthal fibres - smear (WC/AFIP)].
*Sections:
**[http://commons.wikimedia.org/wiki/File:Rosenthal_HE_40x.jpg Rosenthal fibres (WC)].
**[http://moon.ouhsc.edu/kfung/jty1/neurotest/Q19-Ans.htm Rosenthal fibre (ouhsc.edu)].
**[http://path.upmc.edu/cases/case162.html Pilocytic astrocytoma (upmc.edu)].
**[http://path.upmc.edu/cases/case90.html Pilocytic astrocytoma - another case (upmc.edu)].
**[http://path.upmc.edu/cases/case195/images/figure3b.jpg Pilocytic astrocytoma - pennies on a plate (upmc.edu)].<ref>URL: [http://path.upmc.edu/cases/case195.html http://path.upmc.edu/cases/case195.html]. Accessed on: 8 January 2012.</ref>
**[http://path.upmc.edu/cases/case397.html Pilocytic astrocytoma (upmc.edu)].
 
==Stains==
*PAS-D: eosinophilic granular bodies +ve.
 
==IHC==
Features:<ref name=Ref_PSNP84>{{Ref PSNP|84}}</ref>
*GFAP +ve (fibres).
*CD68: may have a significant macrophage component.
*KI-67: may be "high" (~20% ???).
 
==See also==
*[[Neuropathology tumours]].
*[[Astrocytoma]].
 
==References==
{{Reflist|2}}


[[Category:Diagnosis]]
[[Category:Diagnosis]]
[[Category:Neuropathology tumours]]

Revision as of 02:11, 22 December 2013

Pilocytic_astrocytoma]]

General

  • Low-grade astrocytoma - WHO Grade I by definition.
  • Classically in the cerebellum in children; most common glioma in children.[1]
  • The optic glioma associated with neurofibromatosis 1.

Gross

Features:[1]

  • Usually well-circumscribed.
  • Cystic or solid.
  • Do not smear. (Ref. ?)

Microscopic

Features:[2]

  • Classically biphasic (though either may be absent):
    1. Fibrillar.
    2. Microcystic/loose.
  • Hair-like fibres ~ 1 micrometer; pilo- = hair.[3]
    • Best seen on smear or with GFAP IHC.
  • Rosenthal fibres - key feature.
    • May be rare. Not pathognomonic (see below).
  • Eosinophilic granular bodies.
  • Low cellularity - when compared to medulloblastoma and ependymoma.

Notes:

  • +/-Microvascular proliferation.
  • +/-Focal necrosis.
    • Necrosis with pseudopalisading more likely glioblastoma.
  • +/-Mitoses - not significant in the context of the Dx.

DDx (of Rosenthal fibers):[4]

  • Chronic reactive gliosis.
  • Subependymoma.
  • Ganglioma.
  • Alexander's disease (rare leukodystrophy).

DDx of pilocystic astrocytoma (brief):

  • Piloid gliosis.
  • Oligodendroglioma.
  • Glioblastoma (uncommon - but important).

Images

Stains

  • PAS-D: eosinophilic granular bodies +ve.

IHC

Features:[6]

  • GFAP +ve (fibres).
  • CD68: may have a significant macrophage component.
  • KI-67: may be "high" (~20% ???).

See also

References

  1. ↑ 1.0 1.1 Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 82. ISBN 978-0443069826.
  2. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 82-4. ISBN 978-0443069826.
  3. ↑ URL: http://dictionary.reference.com/browse/pilo-. Accessed on: 24 November 2010.
  4. ↑ MUN. 9 Mar 2009.
  5. ↑ URL: http://path.upmc.edu/cases/case195.html. Accessed on: 8 January 2012.
  6. ↑ Perry, Arie; Brat, Daniel J. (2010). Practical Surgical Neuropathology: A Diagnostic Approach: A Volume in the Pattern Recognition series (1st ed.). Churchill Livingstone. pp. 84. ISBN 978-0443069826.
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