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Pilocytic astrocytoma (view source)
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# | 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]] | |||