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'''Pilocytic astrocytoma''' is a low-grade [[astrocytoma]]. It the most common glioma in children. | {{ Infobox diagnosis | ||
| Name = {{PAGENAME}} | |||
| Image = Pilocytic_astrocytoma_-_smear_-_very_high_mag.jpg | |||
| Width = | |||
| Caption = Pilocytic astrocytoma. Smear. [[H&E stain]]. | |||
| Synonyms = | |||
| Micro = | |||
| Subtypes = | |||
| LMDDx = piloid gliosis, [[oligodendroglioma]], [[glioblastoma]] | |||
| Stains = PAS-D +ve (eosinophilic granular bodies) | |||
| IHC = GFAP +ve | |||
| EM = | |||
| Molecular = | |||
| IF = | |||
| Gross = usually cerebellar +/-cystic | |||
| Grossing = | |||
| Site = brain - usu. [[cerebellum]] | |||
| Assdx = | |||
| Syndromes = | |||
| Clinicalhx = | |||
| Signs = | |||
| Symptoms = | |||
| Prevalence = common - esp. in children | |||
| Bloodwork = | |||
| Rads = | |||
| Endoscopy = | |||
| Prognosis = good (WHO Grade I) | |||
| Other = | |||
| ClinDDx = | |||
| Tx = | |||
}} | |||
'''Pilocytic astrocytoma''', abbreviated '''PA''', is a low-grade [[astrocytoma]]. It the most common glioma in children. | |||
==General== | ==General== | ||
*Low-grade [[astrocytoma]] - ''WHO Grade I'' by definition. | *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.<ref name=Ref_PSNP82>{{Ref PSNP|82}}</ref> | *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'' is associated with neurofibromatosis 1. | ||
*Rare variants include [[Pilomyxoid astrocytoma]] and [[Anaplastic pilocytic astrocytoma]]. | |||
==Imaging== | |||
*Well-defined, T2-hyperintense. | |||
*Strong CM enhancement. | |||
*May contain cysts. | |||
*Associated with midline structures. | |||
==Gross== | ==Gross== | ||
Features:<ref name=Ref_PSNP82>{{Ref PSNP|82}}</ref> | Features:<ref name=Ref_PSNP82>{{Ref PSNP|82}}</ref> | ||
*Usually well-circumscribed. | *Usually well-circumscribed, soft. | ||
* | *Can be cystic with mural nodule. | ||
* | *Optic gliomas may present as fusiform mass. | ||
*Occ. calcium deposits and hemosiderin. | |||
==Microscopic== | ==Microscopic== | ||
| Line 30: | Line 69: | ||
*+/-Mitoses - not significant in the context of the Dx. | *+/-Mitoses - not significant in the context of the Dx. | ||
DDx (of Rosenthal fibers):<ref> | DDx (of Rosenthal fibers):<ref>Munoz D. 9 Mar 2009.</ref> | ||
*Chronic reactive gliosis. | *Chronic reactive gliosis. | ||
*Subependymoma. | *Subependymoma. | ||
* | *Ganglioglioma. | ||
*Alexander's disease (rare leukodystrophy). | *Alexander's disease (rare leukodystrophy). | ||
DDx of pilocystic astrocytoma (brief): | DDx of pilocystic astrocytoma (brief): | ||
*Piloid gliosis. | *Piloid gliosis (esp. in sellar lesions). | ||
*Oligodendroglioma. | *[[Oligodendroglioma]]. | ||
*Glioblastoma (uncommon - but important). | *[[Glioblastoma]] (uncommon - but important). | ||
*Tanycytic [[Ependymoma]] | |||
*Pilocytic tumor components may be found in [[Ganglioglioma]], [[DNET]], [[RGNT]] | |||
===Images=== | ===Images=== | ||
| Line 51: | Line 92: | ||
<gallery> | <gallery> | ||
Image:Rosenthal_HE_40x.jpg | Rosenthal fibres. (WC) | Image:Rosenthal_HE_40x.jpg | Rosenthal fibres. (WC) | ||
Image:Pilocytic astrocytoma cell pleomorphism.jpg | Occasional pleomorphism. (WC) | |||
Image:Pilocytic astrocytoma endothelial proliferations.jpg | Microvascular proliferation. (WC) | |||
</gallery> | </gallery> | ||
www: | www: | ||
| Line 67: | Line 110: | ||
*CD68: may have a significant macrophage component. | *CD68: may have a significant macrophage component. | ||
*KI-67: may be "high" (~20% ???). | *KI-67: may be "high" (~20% ???). | ||
*Olig 2: Usually strongly present.<ref name=pmid21193945>{{Cite journal | last1 = Otero | first1 = JJ. | last2 = Rowitch | first2 = D. | last3 = Vandenberg | first3 = S. | title = OLIG2 is differentially expressed in pediatric astrocytic and in ependymal neoplasms. | journal = J Neurooncol | volume = 104 | issue = 2 | pages = 423-38 | month = Sep | year = 2011 | doi = 10.1007/s11060-010-0509-x | PMID = 21193945 }}</ref> | |||
*[[IDH1]] (R132H) -ve. | |||
*[[H3F3A]] (K27M) -ve. | |||
==Molecular== | |||
* 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 (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> | |||
*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> | |||
==Prognosis== | |||
*Excellent (10-year OS: 90%) | |||
*In thalamic/chiasmatic region not so good (incomplete resection, often [[Pilomyxoid astrocytoma]]). | |||
*Primary treatment: surgery. Incomplete resection: RT has to be considered. | |||
**Chx is given in rare cases that are still progredient<ref>{{Cite journal | last1 = Metts | first1 = RD. | last2 = Bartynski | first2 = W. | last3 = Welsh | first3 = CT. | last4 = Kinsman | first4 = S. | last5 = Bredlau | first5 = AL. | title = Bevacizumab Therapy for Pilomyxoid Astrocytoma. | journal = J Pediatr Hematol Oncol | volume = | issue = | pages = | month = Mar | year = 2017 | doi = 10.1097/MPH.0000000000000824 | PMID = 28338567 }}</ref> | |||
==See also== | ==See also== | ||