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Neuropathology tumours (view source)
Revision as of 05:38, 24 November 2010
, 05:38, 24 November 2010→Pilocytic astrocytoma: more, +pilomyxoid astrocytoma
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==Pilocytic astrocytoma== | ==Pilocytic astrocytoma== | ||
===General=== | ===General=== | ||
*Low-grade astrocytoma. | *Low-grade astrocytoma. | ||
*Classically in the cerebellum in children. | *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. | *The ''optic glioma'' associated with neurofibromatosis 1. | ||
===Gross=== | ===Gross=== | ||
*Do '''not''' smear. | Features:<ref>{{PSNP|82}}</ref> | ||
*Usually well-circumscribed. | |||
*Cystic ''or'' solid. | |||
*Do '''not''' smear. (Ref. ?) | |||
===Microscopic=== | ===Microscopic=== | ||
Features: | 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'''. | *Rosenthal fibres - '''key feature'''. | ||
**May be rare. Not pathognomonic (see below). | |||
*Eosinophilic granular bodies. | *Eosinophilic granular bodies. | ||
*Low cellularity - when compared to medulloblastoma and ependymoma. | *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. | |||
Images: | Images: | ||
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*Ganglioma. | *Ganglioma. | ||
*Alexander's disease (rare leukodystrophy). | *Alexander's disease (rare leukodystrophy). | ||
DDx of pilocystic astrocytoma (brief): | |||
*Piloid gliosis. | |||
*Oligodendroglioma. | |||
*Glioblastoma (uncommon - but important). | |||
===IHC/special stains=== | |||
Features:<ref name=Ref_PSNP84>{{Ref PSNP|84}}</ref> | |||
*GFAP +ve (fibres). | |||
*PAS-D: eosinophilic granular bodies +ve. | |||
*CD68: may have a significant macrophage component. | |||
*KI-67: may be "high" (~20% ???). | |||
===Grading=== | |||
*''WHO Grade I'' by definition. | |||
==Pilomyxoid astrocytoma== | |||
===General=== | |||
Features:<ref name=Ref_PSNP86>{{Ref PSNP|86}}</ref> | |||
*Considered to be a variant of ''pilocytic astrocytoma''. | |||
*Childhood or adolescence. | |||
===Gross=== | |||
Features:<ref name=Ref_PSNP86>{{Ref PSNP|86}}</ref> | |||
*Classically - hypothalamic location. | |||
*Solid. | |||
*Well-circumscribed. | |||
===Microscopic=== | |||
Features:<ref name=Ref_PSNP86>{{Ref PSNP|86}}</ref> | |||
*Consists of small round/ovoid bland cells in a myxoid stroma. | |||
*Hair-like fibres ~ 1 micrometer. | |||
**Often difficult to appreciate on standard (H&E) histologic sections. | |||
*Usually angiocentric (surround blood vessel) - '''key feature'''. | |||
Notes:<ref name=Ref_PSNP86>{{Ref PSNP|86}}</ref> | |||
*Rosenthal fibres are absent - '''key negative'''. | |||
*Monophasic (unlike classical pilocytic astrocytomas) - '''key negative'''. | |||
*May rarely have eosinophilic granular bodies. | |||
===Grading=== | |||
*''WHO Grade II'' by definition.<ref name=Ref_PSNP86>{{Ref PSNP|86}}</ref> | |||
==Atypical teratoid/rhabdoid tumour== | ==Atypical teratoid/rhabdoid tumour== | ||