Difference between revisions of "High-grade astrocytoma with piloid features"

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'''High-grade astrocytoma with piloid features''' is a rare [[Glioma|glial]] tumor which often requires methylation analyis to secure diagnosis. There is currently no definitive grading, but clinical behaviour suggests WHO CNS grade 3.
{{ Infobox diagnosis
| Name      = {{PAGENAME}}
| Image      = Pilocytic astrocytoma with anaplastic features.jpg
| Width      =
| Caption    = High-grade astrocytoma with piloid features. [[H&E stain]].
| Synonyms  =
| Micro      =
| Subtypes  =
| LMDDx      = [[astrocytoma]], [[PXA]], [[glioblastoma]]
| Stains    = PAS-D +ve (eosinophilic granular bodies)
| IHC        = GFAP +ve
| EM        =
| Molecular  =
| IF        =
| Gross      = usually cerebellar
| Grossing  =
| Site      = brain - usu. [[cerebellum]]
| Assdx      =
| Syndromes  =
| Clinicalhx =
| Signs      =
| Symptoms  =
| Prevalence = very rare - esp. in children
| Bloodwork  =
| Rads      =
| Endoscopy  =
| Prognosis  = poor (analog to WHO Grade III)
| Other      =
| ClinDDx    =
| Tx        =
}}
 
'''High-grade astrocytoma with piloid features''' (HGAP) is a rare [[Glioma|glial]] tumor which often requires methylation analyis to secure diagnosis. There is currently no definitive grading, but clinical behaviour suggests WHO CNS grade 3.




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*Imaging may be similiar to [[Glioblastoma]].
*Imaging may be similiar to [[Glioblastoma]].
*5-year OS: 50%.
*5-year OS: 50%.
*De novo cases in the setting of neurofibromatosis 1 reported.
*Tumors may have history of previous radiation.


=Histology=
=Histology=
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*Perivascular lymphocytic cuffing.
*Perivascular lymphocytic cuffing.
*Necrosis may be present.
*Necrosis may be present.
==Images==
<gallery>
Image:Pilocytic astrocytoma with anaplastic features.jpg | HGAP, [[FFPE]] specimen, HE (WC).
Image:Pilocytic astrocytoma with anaplastic features mimicking focally a GBM.jpg | Vacular proliferations and necrosis in HGAP mimicking [[GBM]] (WC).
</gallery>


=IHC=
=IHC=
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*TERT promotor mutations are rare.
*TERT promotor mutations are rare.
*Absence of IDH1/2 hotspot mutation.
*Absence of IDH1/2 hotspot mutation.
=Prognosis=
*Poor, but better than conventional glioblastoma.<ref>{{Cite journal  | last1 = Rodriguez | first1 = FJ. | last2 = Scheithauer | first2 = BW. | last3 = Burger | first3 = PC. | last4 = Jenkins | first4 = S. | last5 = Giannini | first5 = C. | title = Anaplasia in pilocytic astrocytoma predicts aggressive behavior. | journal = Am J Surg Pathol | volume = 34 | issue = 2 | pages = 147-60 | month = Feb | year = 2010 | doi = 10.1097/PAS.0b013e3181c75238 | PMID = 20061938 }}</ref>
*Prognostic unfavourable paramters include: Necrosis, Mitoses and previous radiation.




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

Latest revision as of 13:54, 17 October 2022

High-grade astrocytoma with piloid features
Diagnosis in short

High-grade astrocytoma with piloid features. H&E stain.
LM DDx astrocytoma, PXA, glioblastoma
Stains PAS-D +ve (eosinophilic granular bodies)
IHC GFAP +ve
Gross usually cerebellar
Site brain - usu. cerebellum

Prevalence very rare - esp. in children
Prognosis poor (analog to WHO Grade III)


High-grade astrocytoma with piloid features (HGAP) is a rare glial tumor which often requires methylation analyis to secure diagnosis. There is currently no definitive grading, but clinical behaviour suggests WHO CNS grade 3.


Clinical

  • Rare (1-3% of all brain tumor in adults).
  • Usu. posterior fossa (75%).
  • Supratentorial or spinal locations possible.
  • Imaging may be similiar to Glioblastoma.
  • 5-year OS: 50%.
  • De novo cases in the setting of neurofibromatosis 1 reported.
  • Tumors may have history of previous radiation.

Histology

  • Often so variable, so molecular testing is essential to secure diagnosis.
  • Astrocytic nature of tumor cells.
  • Frequent mitoses.
  • Elongated glial tumor cell processes ("piloid").
  • Rosenthal fibers or eosinophilic granular bodies.
  • Perivascular lymphocytic cuffing.
  • Necrosis may be present.

Images

IHC

  • GFAP+ve.
  • ATRX: nuclear loss in approx. 40%.


Molecular

  • DNA Methylation profile of high-grade astrocytoma with piloid features is essential for diagnosis.
  • MAPK genes often altered (NF1, BRAF fusion, FGFR1, KRAS).
  • CDKN2A/B homozygous deletion.
  • CDK4 amplification.
  • TERT promotor mutations are rare.
  • Absence of IDH1/2 hotspot mutation.

Prognosis

  • Poor, but better than conventional glioblastoma.[1]
  • Prognostic unfavourable paramters include: Necrosis, Mitoses and previous radiation.


DDx:

See also

  1. Rodriguez, FJ.; Scheithauer, BW.; Burger, PC.; Jenkins, S.; Giannini, C. (Feb 2010). "Anaplasia in pilocytic astrocytoma predicts aggressive behavior.". Am J Surg Pathol 34 (2): 147-60. doi:10.1097/PAS.0b013e3181c75238. PMID 20061938.