Difference between revisions of "Pilocytic astrocytoma"

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==Molecular==
==Molecular==
* Alteration usually associated with the MAPK pathway.
* Almost all alteration associated with the MAPK pathway.<ref>{{Cite journal  | last1 = Collins | first1 = VP. | last2 = Jones | first2 = DT. | last3 = Giannini | first3 = C. | title = Pilocytic astrocytoma: pathology, molecular mechanisms and markers. | journal = Acta Neuropathol | volume = 129 | issue = 6 | pages = 775-88 | month = Jun | year = 2015 | doi = 10.1007/s00401-015-1410-7 | PMID = 25792358 }}</ref>
* KIAA1549-BRAF fusion transcripts most common in sporadic PA.
* KIAA1549-BRAF fusion transcripts most common in sporadic PA (up to 2/3 of all cases).
**DDx: Fusion reported in rare Diffuse Leptomeingeal Glioneuronal Tumors and Oligodendroglioma.
* Rarely BRAF, KRAS or FGFR1 mutations, NTRK2, SRGAP3-RAF1 or FAM131B-BRAF fusions.<ref>{{Cite journal  | last1 = Jones | first1 = DT. | last2 = Hutter | first2 = B. | last3 = Jäger | first3 = N. | last4 = Korshunov | first4 = A. | last5 = Kool | first5 = M. | last6 = Warnatz | first6 = HJ. | last7 = Zichner | first7 = T. | last8 = Lambert | first8 = SR. | last9 = Ryzhova | first9 = M. | title = Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma. | journal = Nat Genet | volume = 45 | issue = 8 | pages = 927-32 | month = Aug | year = 2013 | doi = 10.1038/ng.2682 | PMID = 23817572 }}</ref><ref>{{Cite journal  | last1 = Cin | first1 = H. | last2 = Meyer | first2 = C. | last3 = Herr | first3 = R. | last4 = Janzarik | first4 = WG. | last5 = Lambert | first5 = S. | last6 = Jones | first6 = DT. | last7 = Jacob | first7 = K. | last8 = Benner | first8 = A. | last9 = Witt | first9 = H. | title = Oncogenic FAM131B-BRAF fusion resulting from 7q34 deletion comprises an alternative mechanism of MAPK pathway activation in pilocytic astrocytoma. | journal = Acta Neuropathol | volume = 121 | issue = 6 | pages = 763-74 | month = Jun | year = 2011 | doi = 10.1007/s00401-011-0817-z | PMID = 21424530 }}</ref>
* Rarely BRAF, KRAS or FGFR1 mutations, NTRK2, SRGAP3-RAF1 or FAM131B-BRAF fusions.<ref>{{Cite journal  | last1 = Jones | first1 = DT. | last2 = Hutter | first2 = B. | last3 = Jäger | first3 = N. | last4 = Korshunov | first4 = A. | last5 = Kool | first5 = M. | last6 = Warnatz | first6 = HJ. | last7 = Zichner | first7 = T. | last8 = Lambert | first8 = SR. | last9 = Ryzhova | first9 = M. | title = Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma. | journal = Nat Genet | volume = 45 | issue = 8 | pages = 927-32 | month = Aug | year = 2013 | doi = 10.1038/ng.2682 | PMID = 23817572 }}</ref><ref>{{Cite journal  | last1 = Cin | first1 = H. | last2 = Meyer | first2 = C. | last3 = Herr | first3 = R. | last4 = Janzarik | first4 = WG. | last5 = Lambert | first5 = S. | last6 = Jones | first6 = DT. | last7 = Jacob | first7 = K. | last8 = Benner | first8 = A. | last9 = Witt | first9 = H. | title = Oncogenic FAM131B-BRAF fusion resulting from 7q34 deletion comprises an alternative mechanism of MAPK pathway activation in pilocytic astrocytoma. | journal = Acta Neuropathol | volume = 121 | issue = 6 | pages = 763-74 | month = Jun | year = 2011 | doi = 10.1007/s00401-011-0817-z | PMID = 21424530 }}</ref>
*Up to 15% of all [[NF1]] patients develop a PA ("optic glioma" as predilection).<ref>{{Cite journal  | last1 = Friedrich | first1 = RE. | last2 = Nuding | first2 = MA. | title = Optic Pathway Glioma and Cerebral Focal Abnormal Signal Intensity in Patients with Neurofibromatosis Type 1: Characteristics, Treatment Choices and Follow-up in 134 Affected Individuals and a Brief Review of the Literature. | journal = Anticancer Res | volume = 36 | issue = 8 | pages = 4095-121 | month = Aug | year = 2016 | doi =  | PMID = 27466519 }}</ref>
*Rare reports of PA in Noonan-Syndrome (PTPN11 mutation).<ref>{{Cite journal  | last1 = Jones | first1 = DT. | last2 = Hutter | first2 = B. | last3 = Jäger | first3 = N. | last4 = Korshunov | first4 = A. | last5 = Kool | first5 = M. | last6 = Warnatz | first6 = HJ. | last7 = Zichner | first7 = T. | last8 = Lambert | first8 = SR. | last9 = Ryzhova | first9 = M. | title = Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma. | journal = Nat Genet | volume = 45 | issue = 8 | pages = 927-32 | month = Aug | year = 2013 | doi = 10.1038/ng.2682 | PMID = 23817572 }}</ref>


==See also==
==See also==

Revision as of 07:30, 10 April 2017

Pilocytic astrocytoma
Diagnosis in short

Pilocytic astrocytoma. Smear. H&E stain.
LM DDx piloid gliosis, oligodendroglioma, glioblastoma
Stains PAS-D +ve (eosinophilic granular bodies)
IHC GFAP +ve
Gross usually cerebellar +/-cystic
Site brain - usu. cerebellum

Prevalence common - esp. in children
Prognosis good (WHO Grade I)

Pilocytic astrocytoma, abbreviated PA, is a low-grade astrocytoma. It the most common glioma in children.

General

  • Low-grade astrocytoma - WHO Grade I by definition, but rare anaplastic forms have been described.
  • Classically in the cerebellum in children; most common glioma in children.[1]
  • The optic glioma is associated with neurofibromatosis 1.
  • Usually enhances after CM application

Gross

Features:[1]

  • Usually well-circumscribed.
  • Often cystic with mural nodule.

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.
  • Ganglioglioma.
  • Alexander's disease (rare leukodystrophy).

DDx of pilocystic astrocytoma (brief):

Images

Smears

Sections

www:

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% ???).
  • Olig 2: Usually strongly present.[7]

Molecular

  • Almost all alteration associated with the MAPK pathway.[8]
  • KIAA1549-BRAF fusion transcripts most common in sporadic PA (up to 2/3 of all cases).
    • DDx: Fusion reported in rare Diffuse Leptomeingeal Glioneuronal Tumors and Oligodendroglioma.
  • Rarely BRAF, KRAS or FGFR1 mutations, NTRK2, SRGAP3-RAF1 or FAM131B-BRAF fusions.[9][10]
  • Up to 15% of all NF1 patients develop a PA ("optic glioma" as predilection).[11]
  • Rare reports of PA in Noonan-Syndrome (PTPN11 mutation).[12]

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. Munoz D. 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.
  7. Otero, JJ.; Rowitch, D.; Vandenberg, S. (Sep 2011). "OLIG2 is differentially expressed in pediatric astrocytic and in ependymal neoplasms.". J Neurooncol 104 (2): 423-38. doi:10.1007/s11060-010-0509-x. PMID 21193945.
  8. Collins, VP.; Jones, DT.; Giannini, C. (Jun 2015). "Pilocytic astrocytoma: pathology, molecular mechanisms and markers.". Acta Neuropathol 129 (6): 775-88. doi:10.1007/s00401-015-1410-7. PMID 25792358.
  9. Jones, DT.; Hutter, B.; Jäger, N.; Korshunov, A.; Kool, M.; Warnatz, HJ.; Zichner, T.; Lambert, SR. et al. (Aug 2013). "Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma.". Nat Genet 45 (8): 927-32. doi:10.1038/ng.2682. PMID 23817572.
  10. Cin, H.; Meyer, C.; Herr, R.; Janzarik, WG.; Lambert, S.; Jones, DT.; Jacob, K.; Benner, A. et al. (Jun 2011). "Oncogenic FAM131B-BRAF fusion resulting from 7q34 deletion comprises an alternative mechanism of MAPK pathway activation in pilocytic astrocytoma.". Acta Neuropathol 121 (6): 763-74. doi:10.1007/s00401-011-0817-z. PMID 21424530.
  11. Friedrich, RE.; Nuding, MA. (Aug 2016). "Optic Pathway Glioma and Cerebral Focal Abnormal Signal Intensity in Patients with Neurofibromatosis Type 1: Characteristics, Treatment Choices and Follow-up in 134 Affected Individuals and a Brief Review of the Literature.". Anticancer Res 36 (8): 4095-121. PMID 27466519.
  12. Jones, DT.; Hutter, B.; Jäger, N.; Korshunov, A.; Kool, M.; Warnatz, HJ.; Zichner, T.; Lambert, SR. et al. (Aug 2013). "Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma.". Nat Genet 45 (8): 927-32. doi:10.1038/ng.2682. PMID 23817572.