CNS5:Pleomorphic xanthoastrocytoma: Difference between revisions
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{{DISPLAYTITLE:Pleomorphic xanthoastrocytoma}} | {{DISPLAYTITLE:Pleomorphic xanthoastrocytoma}} | ||
[[CNS5:Table_of_Contents|Central Nervous System Tumours (WHO Classification, 5th ed.)]] | |||
<span style="color:#0070C0">(''General Instructions – The focus of these pages is the clinically significant genetic alterations in each disease type. This is based on up-to-date knowledge from multiple resources such as PubMed and the WHO classification books. The CCGA is meant to be a supplemental resource to the WHO classification books; the CCGA captures in a continually updated wiki-stye manner the current genetics/genomics knowledge of each disease, which evolves more rapidly than books can be revised and published. If the same disease is described in multiple WHO classification books, the genetics-related information for that disease will be consolidated into a single main page that has this template (other pages would only contain a link to this main page). | <span style="color:#0070C0">(''General Instructions – The focus of these pages is the clinically significant genetic alterations in each disease type. This is based on up-to-date knowledge from multiple resources such as PubMed and the WHO classification books. The CCGA is meant to be a supplemental resource to the WHO classification books; the CCGA captures in a continually updated wiki-stye manner the current genetics/genomics knowledge of each disease, which evolves more rapidly than books can be revised and published. If the same disease is described in multiple WHO classification books, the genetics-related information for that disease will be consolidated into a single main page that has this template (other pages would only contain a link to this main page).'' </span> | ||
==Primary Author(s)*== | ==Primary Author(s)*== | ||
Wahab A. Khan, PhD, FACMG, Dartmouth Health <span style="color:#0070C0"> </span> | |||
==WHO Classification of Disease== | ==WHO Classification of Disease== | ||
| Line 29: | Line 28: | ||
|} | |} | ||
== | == Related Terminology - Pleomorphic xanthoastrocytoma (PXA) == | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ | ||
|Acceptable | |Acceptable | ||
| | |N/A | ||
|- | |- | ||
|Not Recommended | |Not Recommended | ||
| | |Pleomorphic xanthoastrocytoma with anaplastic features; anaplastic pleomorphic xanthoastrocytoma (for CNS WHO grade 3) | ||
|} | |} | ||
==Gene Rearrangements== | ==Gene Rearrangements == | ||
{| class="wikitable sortable" | {| class="wikitable sortable" | ||
|- | |- | ||
| Line 64: | Line 49: | ||
!Clinical Relevance Details/Other Notes | !Clinical Relevance Details/Other Notes | ||
|- | |- | ||
| | |''BRAF''||''BRAF''-''KIAA1549'' (rare), ''RAF1'' fusions, ''NTRK2''/''ALK''/''NTRK1'' (very rare in PXA)||Aberrant MAPK pathway activation (i.e BRAF p.V600E variant)||N/A | ||
|< | |BRAF p.V600E: Common in PXA, Fusions: Rare | ||
| | |D, P, T | ||
| | |Yes (WHO 2021/2025, NCCN 2023)<ref>{{Cite journal|last=d’Amati|first=Antonio|last2=Bargiacchi|first2=Lavinia|last3=Rossi|first3=Sabrina|last4=Carai|first4=Andrea|last5=Bertero|first5=Luca|last6=Barresi|first6=Valeria|last7=Errico|first7=Maria Elena|last8=Buccoliero|first8=Anna Maria|last9=Asioli|first9=Sofia|date=2024-03-13|title=Pediatric CNS tumors and 2021 WHO classification: what do oncologists need from pathologists?|url=https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2024.1268038/full|journal=Frontiers in Molecular Neuroscience|language=English|volume=17|doi=10.3389/fnmol.2024.1268038|issn=1662-5099}}</ref> | ||
| | |BRAF p.V600E is diagnostic and predictive; kinase fusions targetable in rare cases<ref name=":0">{{Cite journal|last=Phillips|first=Joanna J.|last2=Gong|first2=Henry|last3=Chen|first3=Katharine|last4=Joseph|first4=Nancy M.|last5=van Ziffle|first5=Jessica|last6=Bastian|first6=Boris C.|last7=Grenert|first7=James P.|last8=Kline|first8=Cassie N.|last9=Mueller|first9=Sabine|date=2019-01|title=The genetic landscape of anaplastic pleomorphic xanthoastrocytoma|url=https://pubmed.ncbi.nlm.nih.gov/30051528|journal=Brain Pathology (Zurich, Switzerland)|volume=29|issue=1|pages=85–96|doi=10.1111/bpa.12639|issn=1750-3639|pmc=7837273|pmid=30051528}}</ref><ref>{{Cite journal|last=Vaubel|first=Rachael A.|last2=Caron|first2=Alissa A.|last3=Yamada|first3=Seiji|last4=Decker|first4=Paul A.|last5=Eckel Passow|first5=Jeanette E.|last6=Rodriguez|first6=Fausto J.|last7=Nageswara Rao|first7=Amulya A.|last8=Lachance|first8=Daniel|last9=Parney|first9=Ian|date=2018-03|title=Recurrent copy number alterations in low-grade and anaplastic pleomorphic xanthoastrocytoma with and without BRAF V600E mutation|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC5807227/|journal=Brain Pathology (Zurich, Switzerland)|volume=28|issue=2|pages=172–182|doi=10.1111/bpa.12495|issn=1750-3639|pmc=5807227|pmid=28181325}}</ref> <ref>{{Cite journal|last=Tian|first=Lei|last2=Sun|first2=Wei|last3=Lou|first3=Lei|last4=Wang|first4=Wenyan|last5=Li|first5=Yanan|last6=Zhou|first6=Huandi|last7=Xiao|first7=Zhiqing|last8=Xue|first8=Xiaoying|date=2025|title=Pleomorphic xanthoastrocytoma with multiple recurrences and continuous malignant progression to bone metastasis: a case report|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC12174448/|journal=Frontiers in Surgery|volume=12|pages=1595199|doi=10.3389/fsurg.2025.1595199|issn=2296-875X|pmc=12174448|pmid=40535548}}</ref><ref>{{Cite journal|last=Di Nunno|first=Vincenzo|last2=Gatto|first2=Lidia|last3=Tosoni|first3=Alicia|last4=Bartolini|first4=Stefania|last5=Franceschi|first5=Enrico|date=2022|title=Implications of BRAF V600E mutation in gliomas: Molecular considerations, prognostic value and treatment evolution|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC9846085/|journal=Frontiers in Oncology|volume=12|pages=1067252|doi=10.3389/fonc.2022.1067252|issn=2234-943X|pmc=9846085|pmid=36686797}}</ref> | ||
|- | |- | ||
| | |''CDKN2A''/''B'' | ||
|N/A | |||
| | |Loss leads to cell cycle dysregulation | ||
|''CDKN2A''/''B'' homozygous deletion (9p21); chr7 gain; chr10/22 loss | |||
| | |Common | ||
| | |D, P | ||
| | |Yes (WHO, NCCN—context specific) | ||
|Co-occurrence with BRAF p.V600E supports PXA diagnosis | |||
|- | |- | ||
| | |TERT | ||
| | |N/A | ||
|Telomerase activation (mainly in anaplastic PXA) | |||
|TERT promoter mutations/amplifications | |||
|Recurrent (15–47% in anaplastic)<ref>{{Cite journal|last=Phillips|first=Joanna J.|last2=Gong|first2=Henry|last3=Chen|first3=Katharine|last4=Joseph|first4=Nancy M.|last5=van Ziffle|first5=Jessica|last6=Bastian|first6=Boris C.|last7=Grenert|first7=James P.|last8=Kline|first8=Cassie N.|last9=Mueller|first9=Sabine|date=2019-01|title=The genetic landscape of anaplastic pleomorphic xanthoastrocytoma|url=https://pubmed.ncbi.nlm.nih.gov/30051528|journal=Brain Pathology (Zurich, Switzerland)|volume=29|issue=1|pages=85–96|doi=10.1111/bpa.12639|issn=1750-3639|pmc=7837273|pmid=30051528}}</ref> | |||
|P (poor; recurrence risk) | |||
|Yes (WHO, NCCN-context specefic) | |||
|Seen mainly in grade 3/anaplastic; adverse outcome<ref name=":0" /> | |||
<br /> | |||
|- | |- | ||
| | |NTRK2, ALK, RAF1 | ||
| | |Fusions: NACC2-NTRK2, BEND5-NTRK2, PPP1CB-ALK, etc. | ||
| | |MAPK pathway activation via kinase fusions | ||
| | |Variable; not associated with classic chr alterations | ||
| | |Rare (<5%)<ref>{{Cite journal|last=Galbraith|first=Kristyn|last2=Serrano|first2=Jonathan|last3=Shen|first3=Guomiao|last4=Tran|first4=Ivy|last5=Slocum|first5=Cheyanne C.|last6=Ketchum|first6=Courtney|last7=Abdullaev|first7=Zied|last8=Turakulov|first8=Rust|last9=Bale|first9=Tejus|date=2024-01-02|title=Impact of Rare and Multiple Concurrent Gene Fusions on Diagnostic DNA Methylation Classifier in Brain Tumors|url=https://pubmed.ncbi.nlm.nih.gov/37870438|journal=Molecular cancer research: MCR|volume=22|issue=1|pages=21–28|doi=10.1158/1541-7786.MCR-23-0627|issn=1557-3125|pmc=10942665|pmid=37870438}}</ref> | ||
| | |D | ||
| | |Context-dependent ( e.g. For patients with CNS tumors who harbor NTRK fusions, TRK inhibitors such as larotrectinib or repotrectinib are considered a preferred therapy, regardless of histology, if other options are limited) NCCN CNS Cancer guidelines | ||
| | |Reported in individual cases; more common in glioneuronal/low-grade gliomas | ||
|} | |} | ||
==Individual Region Genomic Gain/Loss/LOH== | ==Individual Region Genomic Gain/Loss/LOH== | ||
{| class="wikitable sortable" | {| class="wikitable sortable" | ||
|- | |- | ||
!Chr #!! | !Chr #!!Gain, Loss, Amp, LOH!!Minimal Region Cytoband and/or Genomic Coordinates [Genome Build; Size]!!Relevant Gene(s) | ||
! | !Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | ||
! | !Established Clinical Significance Per Guidelines - Yes or No (Source) | ||
! | !Clinical Relevance Details/Other Notes | ||
|- | |- | ||
| | |9p21 | ||
|Homozygous loss, LOH | |||
| | |9p21.3; chr9:21,900,000-22,300,000 (GRCh38; ~400Kb) | ||
|CDKN2A, CDKN2B | |||
|D, P | |||
| | |Yes (WHO CNS5, NCCN) | ||
|Defining PXA feature; occurs in >85% of cases<ref name=":1" /> | |||
| | |||
| | |||
|< | |||
|- | |- | ||
| | |7 | ||
|Gain | |||
| | |Chr7 whole arm or segmental (varies) | ||
| | |EGFR not typically amplified) | ||
|D | |||
|< | |No (however, frequently mentioned in literature as a recurrent copy number change in PXA<ref>{{Cite journal|last=Vaubel|first=Rachael|last2=Zschernack|first2=Valentina|last3=Tran|first3=Quynh T.|last4=Jenkins|first4=Sarah|last5=Caron|first5=Alissa|last6=Milosevic|first6=Dragana|last7=Smadbeck|first7=James|last8=Vasmatzis|first8=George|last9=Kandels|first9=Daniela|date=2021-01|title=Biology and grading of pleomorphic xanthoastrocytoma-what have we learned about it?|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC8018001/|journal=Brain Pathology (Zurich, Switzerland)|volume=31|issue=1|pages=20–32|doi=10.1111/bpa.12874|issn=1750-3639|pmc=8018001|pmid=32619305}}</ref> | ||
|Trisomy, supports diagnosis; also seen in other gliomas | |||
| | |||
| | |||
| | |||
|- | |- | ||
| | |22 | ||
|Loss | |||
| | |Whole chr22 (varied cytoband, arm) | ||
| | |NF2, others | ||
|D | |||
| | |No (not guideline-specific, recurrent in PXA) | ||
|Frequently reported, may occur with other losses | |||
| | |||
| | |||
|- | |- | ||
| | |8p | ||
| | |Loss | ||
| | |chr 8p (varied region) | ||
| | |Varies | ||
| | |P | ||
| | |No | ||
| | |Seen in a subset, less common | ||
|- | |||
|LOH | |||
|Copy-neutral | |||
|Varies (mainly 9p21) | |||
|CDKN2A, CDKN2B | |||
|D, P | |||
|Yes (NCCN) | |||
|copy-neutral LOH; supports diagnosis | |||
|} | |} | ||
==Characteristic Chromosomal or Other Global Mutational Patterns== | ==Characteristic Chromosomal or Other Global Mutational Patterns== | ||
{| class="wikitable sortable" | {| class="wikitable sortable" | ||
|- | |- | ||
!Chromosomal Pattern | !Chromosomal Pattern | ||
!Molecular Pathogenesis | !Molecular Pathogenesis | ||
! | !Prevalence - | ||
Common >20%, Recurrent 5-20% or Rare <5% (Disease) | |||
! | !Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | ||
! | !Established Clinical Significance Per Guidelines - Yes or No (Source) | ||
! | !Clinical Relevance Details/Other Notes | ||
|- | |- | ||
| | |Common chromosome gains: +7, +5, +2, +12, +20, +21, +15 | ||
|Variable; chromosomal hyperdiploidy | |||
|Recurrent (17-20%) | |||
|P | |||
|No | |||
|Whole chromosome gains common; gains of +12 and +21 more common in BRAF V600E tumors; may indicate genomic instability<ref name=":1">Vaubel RA, Caron AA, Yamada S, Decker PA, Eckel Passow JE, Rodriguez FJ, Nageswara Rao AA, Lachance D, Parney I, Jenkins R, Giannini C. Recurrent copy number alterations in low-grade and anaplastic pleomorphic xanthoastrocytoma with and without BRAF V600E mutation. Brain Pathol. 2018 Mar;28(2):172-182. doi: 10.1111/bpa.12495. Epub 2017 Apr 2. PMID: 28181325; PMCID: PMC5807227.</ref> | |||
|- | |- | ||
| | |Whole chromosome loss or cnLOH most commonly involved chromosomes 22, 14, 13, and 10 | ||
|Variable gene losses | |||
| | |Recurrent | ||
| | |P | ||
|< | |No | ||
|Seen in subset; trend toward anaplastic cases<ref name=":1" /> | |||
|- | |- | ||
| | |Complex karyotype with multiple CNVs | ||
| | |Chromosomal instability (CIN) | ||
| | |Common | ||
| | |P | ||
| | |No | ||
| | |Includes polyploidy, subclones, mosaicism; complexity increases at recurrence/progression<ref name=":1" /> | ||
|- | |||
|Pleomorphic xanthoastrocytoma (PXA) not identified as a high‑TMB or focal amplifications. No MSI‑driven marker in PXA. Global mutation pattern in PXA dominated by MAPK activation (BRAF or kinase fusions) plus CDKN2A/B loss | |||
|CDKN2A/B loss and loss of p16/p14ARF tumor suppressors; cell cycle dysregulation | |||
|Common | |||
|P,D | |||
|Yes | |||
|CDKN2A/B loss defining feature of PXA; not associated with grade or BRAF status; central to PXA biology | |||
|} | |} | ||
==Gene Mutations (SNV/INDEL)== | ==Gene Mutations (SNV/INDEL)== | ||
<span style="color:#0070C0">''This table is not meant to be an exhaustive list''</span> | |||
{| class="wikitable sortable" | {| class="wikitable sortable" | ||
|- | |- | ||
!Gene!! | !Gene!!Genetic Alteration!!Tumor Suppressor Gene, Oncogene, Other!!Prevalence - | ||
Common >20%, Recurrent 5-20% or Rare <5% (Disease) | |||
! | !Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | ||
! | !Established Clinical Significance Per Guidelines - Yes or No (Source) | ||
! | !Clinical Relevance Details/Other Notes | ||
|- | |- | ||
| | |BRAF | ||
<br /> | <br /> | ||
| | |p.V600E missense activating mutation | ||
| | |Oncogene | ||
| | |Common (~60–80%) | ||
| | |D, P, T | ||
| | |Yes (WHO CNS5, NCCN) | ||
|< | |Specific for PXA, actionable with BRAF/MEK inhibitors; rarely found in diffuse astrocytomas. Favorable prognostic marker<ref name=":2">{{Cite journal|last=Kim|first=Young Zoon|last2=Kim|first2=Chae-Yong|last3=Lim|first3=Do Hoon|date=2022-04|title=The Overview of Practical Guidelines for Gliomas by KSNO, NCCN, and EANO|url=https://pubmed.ncbi.nlm.nih.gov/35545827|journal=Brain Tumor Research and Treatment|volume=10|issue=2|pages=83–93|doi=10.14791/btrt.2022.0001|issn=2288-2405|pmc=9098981|pmid=35545827}}</ref> | ||
|- | |- | ||
| | |TERT | ||
<br /> | <br /> | ||
| | |Promoter mutation | ||
| | |Other | ||
| | |Recurrent | ||
| | |P | ||
| | |Yes (WHO CNS5) | ||
|< | |Associated with anaplastic progression, poor recurrence-free survival, and adverse prognosis in high-grade PXA<ref name=":2" /> | ||
|- | |- | ||
| | |IDH1/IDH2 | ||
| | |Missense (R132H, etc) | ||
| | |Other | ||
| | |Absent in classic PXA | ||
|< | |D | ||
|Yes (WHO CNS5 for differential diagnosis) | |||
|Absence confirms classic PXA; if present, suggests diffuse astrocytoma not PXA<ref>Yamada S, Kipp BR, Voss JS, Giannini C, Raghunathan A. Combined "Infiltrating Astrocytoma/Pleomorphic Xanthoastrocytoma" Harboring IDH1 R132H and BRAF V600E Mutations. Am J Surg Pathol. 2016 Feb;40(2):279-84. doi: 10.1097/PAS.0000000000000515. PMID: 26414224.</ref> | |||
|- | |- | ||
| | |NTRK2, ALK | ||
| | |Kinase gene fusions | ||
| | |Oncogene | ||
| | |Rare | ||
| | |T | ||
| | |Yes (FDA/NCCN for fusion-positive CNS tumors, not PXA-specific) | ||
| | |Targetable by TRK/ALK inhibitors (larotrectinib, entrectinib); found chiefly in pediatric BRAF-wildtype PXAs<ref>Fischer JM, Gilbert AR, Galvan EM, Singh AK, Floyd JR, Shah S. Pleomorphic xanthoastrocytoma with anaplasia and BEND5-NTRK2 fusion in a young adult with a history of cranial radiation for childhood rhabdomyosarcoma. Neurooncol Adv. 2025 Mar 8;7(1):vdaf052. doi: 10.1093/noajnl/vdaf052. PMID: 40568680; PMCID: PMC12188291.</ref> | ||
|}Note: A more extensive list of mutations can be found in [https://www.cbioportal.org/ <u>cBioportal</u>], [https://cancer.sanger.ac.uk/cosmic <u>COSMIC</u>], and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content. | |}Note: A more extensive list of mutations can be found in [https://www.cbioportal.org/ <u>cBioportal</u>], [https://cancer.sanger.ac.uk/cosmic <u>COSMIC</u>], and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content. | ||
==Epigenomic Alterations== | ==Epigenomic Alterations== | ||
Dominant epigenomic themes in Pleomorphic xanthoastrocytoma (PXA) are: a distinct methylation class tied to MAPK activation and CDKN2A/B loss, progressive promoter hypermethylation in anaplastic transformation, frequent MGMT promoter methylation, and a relative absence of the H3/ATRX-driven epigenetic programs seen in other glioma subtypes<ref>{{Cite journal|last=Martínez|first=Ramón|last2=Carmona|first2=F. Javier|last3=Vizoso|first3=Miguel|last4=Rohde|first4=Veit|last5=Kirsch|first5=Matthias|last6=Schackert|first6=Gabriele|last7=Ropero|first7=Santiago|last8=Paulus|first8=Werner|last9=Barrantes|first9=Alonso|date=2014-03-20|title=DNA methylation alterations in grade II- and anaplastic pleomorphic xanthoastrocytoma|url=https://pubmed.ncbi.nlm.nih.gov/24650279|journal=BMC cancer|volume=14|pages=213|doi=10.1186/1471-2407-14-213|issn=1471-2407|pmc=4000050|pmid=24650279}}</ref><ref>{{Cite journal|last=Tang|first=Karen|last2=Kurland|first2=David|last3=Vasudevaraja|first3=Varshini|last4=Serrano|first4=Jonathan|last5=Delorenzo|first5=Michael|last6=Radmanesh|first6=Alireza|last7=Thomas|first7=Cheddhi|last8=Spino|first8=Marissa|last9=Gardner|first9=Sharon|date=2020-08-01|title=Exploring DNA Methylation for Prognosis and Analyzing the Tumor Microenvironment in Pleomorphic Xanthoastrocytoma|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC8453609/|journal=Journal of Neuropathology and Experimental Neurology|volume=79|issue=8|pages=880–890|doi=10.1093/jnen/nlaa051|issn=1554-6578|pmc=8453609|pmid=32594172}}</ref>. | |||
==Genes and Main Pathways Involved== | ==Genes and Main Pathways Involved== | ||
{| class="wikitable sortable" | {| class="wikitable sortable" | ||
|- | |- | ||
!Gene; Genetic Alteration!!Pathway!!Pathophysiologic Outcome | !Gene; Genetic Alteration!!Pathway!!Pathophysiologic Outcome | ||
|- | |- | ||
| | |''BRAF'' and ''MAP2K1''; Activating mutations | ||
| | |MAPK signaling | ||
| | |Increased cell growth and proliferation | ||
|- | |- | ||
| | |''CDKN2A''; Inactivating mutations | ||
| | |Cell cycle regulation | ||
| | |Unregulated cell division | ||
|- | |- | ||
| | |TERT promoter mutations or amplification | ||
| | |TERT – Telomere maintenance pathway | ||
|Activate telomerase and support immortalization via the telomere maintenance pathway | |||
| | |||
|} | |} | ||
==Genetic Diagnostic Testing Methods== | ==Genetic Diagnostic Testing Methods== | ||
Diagnostic workup for suspected PXA typically includes BRAF mutation testing, robust assessment of CDKN2A/B deletion (preferably via SNP-microarray or NGS/ddPCR), and DNA methylation profiling, with extended NGS/fusion testing where needed<ref>https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2024.1268038/full</ref> | |||
==Familial Forms== | ==Familial Forms== | ||
For most PXAs, no inherited/familial cause is identified, and they are considered sporadic tumors. | |||
==Additional Information== | ==Additional Information== | ||
PXA belongs to a specific DNA methylation class characterized by BRAF pathway activation (usually BRAF p.V600E) and near‑universal CDKN2A/B homozygous deletion, and is typically IDH1/2‑ and H3‑wildtype; methylation profiling is increasingly used to confirm this integrated molecular diagnosis and to distinguish PXA from pilocytic astrocytoma and epithelioid glioblastoma<ref>{{Cite journal|last=Dampier|first=Christopher H.|last2=Shah|first2=Niharika|last3=Galbraith|first3=Kristyn|last4=Ebrahimi|first4=Azadeh|last5=Neto|first5=Osorio Lopes Abath|last6=Abdullaev|first6=Zied|last7=Alexandrescu|first7=Sanda|last8=Andreiuolo|first8=Felipe|last9=Armstrong|first9=Terri|date=2025|title=Molecular, histologic, and clinical characterization of methylation class pleomorphic xanthoastrocytoma: An analysis of 469 tumors|url=https://pubmed.ncbi.nlm.nih.gov/40735274|journal=Neuro-Oncology Advances|volume=7|issue=1|pages=vdaf089|doi=10.1093/noajnl/vdaf089|issn=2632-2498|pmc=12305539|pmid=40735274}}</ref>. | |||
==Links== | ==Links== | ||
[https://www.cancer.gov/rare-brain-spine-tumor/tumors/pleomorphic-xanthroastrocytoma Pleomorphic Xanthoastrocytoma (PXA) and Other BRAF-Altered Tumors: Diagnosis and Treatment - NCI] | |||
==References== | ==References== | ||
<references /> | |||
==Notes== | ==Notes== | ||
Khan WA: “Pleomorphic xanthoastrocytoma”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated {{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}, <nowiki>https://ccga.io/index.php/CNS5:Pleomorphic xanthoastrocytoma</nowiki>. | |||
[[Category:CNS5]] | |||
[[Category:DISEASE]] | |||
[[Category:Diseases P]] | |||
[[Category:CNS5]][[Category:DISEASE]][[Category:Diseases P]] | |||
Latest revision as of 19:51, 25 February 2026
Central Nervous System Tumours (WHO Classification, 5th ed.)
(General Instructions – The focus of these pages is the clinically significant genetic alterations in each disease type. This is based on up-to-date knowledge from multiple resources such as PubMed and the WHO classification books. The CCGA is meant to be a supplemental resource to the WHO classification books; the CCGA captures in a continually updated wiki-stye manner the current genetics/genomics knowledge of each disease, which evolves more rapidly than books can be revised and published. If the same disease is described in multiple WHO classification books, the genetics-related information for that disease will be consolidated into a single main page that has this template (other pages would only contain a link to this main page).
Primary Author(s)*
Wahab A. Khan, PhD, FACMG, Dartmouth Health
WHO Classification of Disease
| Structure | Disease |
|---|---|
| Book | Central Nervous System Tumours (5th ed.) |
| Category | Gliomas, glioneuronal tumours, and neuronal tumours |
| Family | Gliomas, glioneuronal tumours, and neuronal tumours |
| Type | Circumscribed astrocytic gliomas |
| Subtype(s) | Pleomorphic xanthoastrocytoma |
Related Terminology - Pleomorphic xanthoastrocytoma (PXA)
| Acceptable | N/A |
| Not Recommended | Pleomorphic xanthoastrocytoma with anaplastic features; anaplastic pleomorphic xanthoastrocytoma (for CNS WHO grade 3) |
Gene Rearrangements
| Driver Gene | Fusion(s) and Common Partner Genes | Molecular Pathogenesis | Typical Chromosomal Alteration(s) | Prevalence -Common >20%, Recurrent 5-20% or Rare <5% (Disease) | Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | Established Clinical Significance Per Guidelines - Yes or No (Source) | Clinical Relevance Details/Other Notes |
|---|---|---|---|---|---|---|---|
| BRAF | BRAF-KIAA1549 (rare), RAF1 fusions, NTRK2/ALK/NTRK1 (very rare in PXA) | Aberrant MAPK pathway activation (i.e BRAF p.V600E variant) | N/A | BRAF p.V600E: Common in PXA, Fusions: Rare | D, P, T | Yes (WHO 2021/2025, NCCN 2023)[1] | BRAF p.V600E is diagnostic and predictive; kinase fusions targetable in rare cases[2][3] [4][5] |
| CDKN2A/B | N/A | Loss leads to cell cycle dysregulation | CDKN2A/B homozygous deletion (9p21); chr7 gain; chr10/22 loss | Common | D, P | Yes (WHO, NCCN—context specific) | Co-occurrence with BRAF p.V600E supports PXA diagnosis |
| TERT | N/A | Telomerase activation (mainly in anaplastic PXA) | TERT promoter mutations/amplifications | Recurrent (15–47% in anaplastic)[6] | P (poor; recurrence risk) | Yes (WHO, NCCN-context specefic) | Seen mainly in grade 3/anaplastic; adverse outcome[2]
|
| NTRK2, ALK, RAF1 | Fusions: NACC2-NTRK2, BEND5-NTRK2, PPP1CB-ALK, etc. | MAPK pathway activation via kinase fusions | Variable; not associated with classic chr alterations | Rare (<5%)[7] | D | Context-dependent ( e.g. For patients with CNS tumors who harbor NTRK fusions, TRK inhibitors such as larotrectinib or repotrectinib are considered a preferred therapy, regardless of histology, if other options are limited) NCCN CNS Cancer guidelines | Reported in individual cases; more common in glioneuronal/low-grade gliomas |
Individual Region Genomic Gain/Loss/LOH
| Chr # | Gain, Loss, Amp, LOH | Minimal Region Cytoband and/or Genomic Coordinates [Genome Build; Size] | Relevant Gene(s) | Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | Established Clinical Significance Per Guidelines - Yes or No (Source) | Clinical Relevance Details/Other Notes |
|---|---|---|---|---|---|---|
| 9p21 | Homozygous loss, LOH | 9p21.3; chr9:21,900,000-22,300,000 (GRCh38; ~400Kb) | CDKN2A, CDKN2B | D, P | Yes (WHO CNS5, NCCN) | Defining PXA feature; occurs in >85% of cases[8] |
| 7 | Gain | Chr7 whole arm or segmental (varies) | EGFR not typically amplified) | D | No (however, frequently mentioned in literature as a recurrent copy number change in PXA[9] | Trisomy, supports diagnosis; also seen in other gliomas |
| 22 | Loss | Whole chr22 (varied cytoband, arm) | NF2, others | D | No (not guideline-specific, recurrent in PXA) | Frequently reported, may occur with other losses |
| 8p | Loss | chr 8p (varied region) | Varies | P | No | Seen in a subset, less common |
| LOH | Copy-neutral | Varies (mainly 9p21) | CDKN2A, CDKN2B | D, P | Yes (NCCN) | copy-neutral LOH; supports diagnosis |
Characteristic Chromosomal or Other Global Mutational Patterns
| Chromosomal Pattern | Molecular Pathogenesis | Prevalence -
Common >20%, Recurrent 5-20% or Rare <5% (Disease) |
Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | Established Clinical Significance Per Guidelines - Yes or No (Source) | Clinical Relevance Details/Other Notes |
|---|---|---|---|---|---|
| Common chromosome gains: +7, +5, +2, +12, +20, +21, +15 | Variable; chromosomal hyperdiploidy | Recurrent (17-20%) | P | No | Whole chromosome gains common; gains of +12 and +21 more common in BRAF V600E tumors; may indicate genomic instability[8] |
| Whole chromosome loss or cnLOH most commonly involved chromosomes 22, 14, 13, and 10 | Variable gene losses | Recurrent | P | No | Seen in subset; trend toward anaplastic cases[8] |
| Complex karyotype with multiple CNVs | Chromosomal instability (CIN) | Common | P | No | Includes polyploidy, subclones, mosaicism; complexity increases at recurrence/progression[8] |
| Pleomorphic xanthoastrocytoma (PXA) not identified as a high‑TMB or focal amplifications. No MSI‑driven marker in PXA. Global mutation pattern in PXA dominated by MAPK activation (BRAF or kinase fusions) plus CDKN2A/B loss | CDKN2A/B loss and loss of p16/p14ARF tumor suppressors; cell cycle dysregulation | Common | P,D | Yes | CDKN2A/B loss defining feature of PXA; not associated with grade or BRAF status; central to PXA biology |
Gene Mutations (SNV/INDEL)
This table is not meant to be an exhaustive list
| Gene | Genetic Alteration | Tumor Suppressor Gene, Oncogene, Other | Prevalence -
Common >20%, Recurrent 5-20% or Rare <5% (Disease) |
Diagnostic, Prognostic, and Therapeutic Significance - D, P, T | Established Clinical Significance Per Guidelines - Yes or No (Source) | Clinical Relevance Details/Other Notes |
|---|---|---|---|---|---|---|
| BRAF
|
p.V600E missense activating mutation | Oncogene | Common (~60–80%) | D, P, T | Yes (WHO CNS5, NCCN) | Specific for PXA, actionable with BRAF/MEK inhibitors; rarely found in diffuse astrocytomas. Favorable prognostic marker[10] |
| TERT
|
Promoter mutation | Other | Recurrent | P | Yes (WHO CNS5) | Associated with anaplastic progression, poor recurrence-free survival, and adverse prognosis in high-grade PXA[10] |
| IDH1/IDH2 | Missense (R132H, etc) | Other | Absent in classic PXA | D | Yes (WHO CNS5 for differential diagnosis) | Absence confirms classic PXA; if present, suggests diffuse astrocytoma not PXA[11] |
| NTRK2, ALK | Kinase gene fusions | Oncogene | Rare | T | Yes (FDA/NCCN for fusion-positive CNS tumors, not PXA-specific) | Targetable by TRK/ALK inhibitors (larotrectinib, entrectinib); found chiefly in pediatric BRAF-wildtype PXAs[12] |
Note: A more extensive list of mutations can be found in cBioportal, COSMIC, and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content.
Epigenomic Alterations
Dominant epigenomic themes in Pleomorphic xanthoastrocytoma (PXA) are: a distinct methylation class tied to MAPK activation and CDKN2A/B loss, progressive promoter hypermethylation in anaplastic transformation, frequent MGMT promoter methylation, and a relative absence of the H3/ATRX-driven epigenetic programs seen in other glioma subtypes[13][14].
Genes and Main Pathways Involved
| Gene; Genetic Alteration | Pathway | Pathophysiologic Outcome |
|---|---|---|
| BRAF and MAP2K1; Activating mutations | MAPK signaling | Increased cell growth and proliferation |
| CDKN2A; Inactivating mutations | Cell cycle regulation | Unregulated cell division |
| TERT promoter mutations or amplification | TERT – Telomere maintenance pathway | Activate telomerase and support immortalization via the telomere maintenance pathway |
Genetic Diagnostic Testing Methods
Diagnostic workup for suspected PXA typically includes BRAF mutation testing, robust assessment of CDKN2A/B deletion (preferably via SNP-microarray or NGS/ddPCR), and DNA methylation profiling, with extended NGS/fusion testing where needed[15]
Familial Forms
For most PXAs, no inherited/familial cause is identified, and they are considered sporadic tumors.
Additional Information
PXA belongs to a specific DNA methylation class characterized by BRAF pathway activation (usually BRAF p.V600E) and near‑universal CDKN2A/B homozygous deletion, and is typically IDH1/2‑ and H3‑wildtype; methylation profiling is increasingly used to confirm this integrated molecular diagnosis and to distinguish PXA from pilocytic astrocytoma and epithelioid glioblastoma[16].
Links
Pleomorphic Xanthoastrocytoma (PXA) and Other BRAF-Altered Tumors: Diagnosis and Treatment - NCI
References
- ↑ d’Amati, Antonio; et al. (2024-03-13). "Pediatric CNS tumors and 2021 WHO classification: what do oncologists need from pathologists?". Frontiers in Molecular Neuroscience. 17. doi:10.3389/fnmol.2024.1268038. ISSN 1662-5099.
- ↑ 2.0 2.1 Phillips, Joanna J.; et al. (2019-01). "The genetic landscape of anaplastic pleomorphic xanthoastrocytoma". Brain Pathology (Zurich, Switzerland). 29 (1): 85–96. doi:10.1111/bpa.12639. ISSN 1750-3639. PMC 7837273 Check
|pmc=value (help). PMID 30051528. Check date values in:|date=(help) - ↑ Vaubel, Rachael A.; et al. (2018-03). "Recurrent copy number alterations in low-grade and anaplastic pleomorphic xanthoastrocytoma with and without BRAF V600E mutation". Brain Pathology (Zurich, Switzerland). 28 (2): 172–182. doi:10.1111/bpa.12495. ISSN 1750-3639. PMC 5807227. PMID 28181325. Check date values in:
|date=(help) - ↑ Tian, Lei; et al. (2025). "Pleomorphic xanthoastrocytoma with multiple recurrences and continuous malignant progression to bone metastasis: a case report". Frontiers in Surgery. 12: 1595199. doi:10.3389/fsurg.2025.1595199. ISSN 2296-875X. PMC 12174448 Check
|pmc=value (help). PMID 40535548 Check|pmid=value (help). - ↑ Di Nunno, Vincenzo; et al. (2022). "Implications of BRAF V600E mutation in gliomas: Molecular considerations, prognostic value and treatment evolution". Frontiers in Oncology. 12: 1067252. doi:10.3389/fonc.2022.1067252. ISSN 2234-943X. PMC 9846085 Check
|pmc=value (help). PMID 36686797 Check|pmid=value (help). - ↑ Phillips, Joanna J.; et al. (2019-01). "The genetic landscape of anaplastic pleomorphic xanthoastrocytoma". Brain Pathology (Zurich, Switzerland). 29 (1): 85–96. doi:10.1111/bpa.12639. ISSN 1750-3639. PMC 7837273 Check
|pmc=value (help). PMID 30051528. Check date values in:|date=(help) - ↑ Galbraith, Kristyn; et al. (2024-01-02). "Impact of Rare and Multiple Concurrent Gene Fusions on Diagnostic DNA Methylation Classifier in Brain Tumors". Molecular cancer research: MCR. 22 (1): 21–28. doi:10.1158/1541-7786.MCR-23-0627. ISSN 1557-3125. PMC 10942665 Check
|pmc=value (help). PMID 37870438 Check|pmid=value (help). - ↑ 8.0 8.1 8.2 8.3 Vaubel RA, Caron AA, Yamada S, Decker PA, Eckel Passow JE, Rodriguez FJ, Nageswara Rao AA, Lachance D, Parney I, Jenkins R, Giannini C. Recurrent copy number alterations in low-grade and anaplastic pleomorphic xanthoastrocytoma with and without BRAF V600E mutation. Brain Pathol. 2018 Mar;28(2):172-182. doi: 10.1111/bpa.12495. Epub 2017 Apr 2. PMID: 28181325; PMCID: PMC5807227.
- ↑ Vaubel, Rachael; et al. (2021-01). "Biology and grading of pleomorphic xanthoastrocytoma-what have we learned about it?". Brain Pathology (Zurich, Switzerland). 31 (1): 20–32. doi:10.1111/bpa.12874. ISSN 1750-3639. PMC 8018001 Check
|pmc=value (help). PMID 32619305 Check|pmid=value (help). Check date values in:|date=(help) - ↑ 10.0 10.1 Kim, Young Zoon; et al. (2022-04). "The Overview of Practical Guidelines for Gliomas by KSNO, NCCN, and EANO". Brain Tumor Research and Treatment. 10 (2): 83–93. doi:10.14791/btrt.2022.0001. ISSN 2288-2405. PMC 9098981 Check
|pmc=value (help). PMID 35545827 Check|pmid=value (help). Check date values in:|date=(help) - ↑ Yamada S, Kipp BR, Voss JS, Giannini C, Raghunathan A. Combined "Infiltrating Astrocytoma/Pleomorphic Xanthoastrocytoma" Harboring IDH1 R132H and BRAF V600E Mutations. Am J Surg Pathol. 2016 Feb;40(2):279-84. doi: 10.1097/PAS.0000000000000515. PMID: 26414224.
- ↑ Fischer JM, Gilbert AR, Galvan EM, Singh AK, Floyd JR, Shah S. Pleomorphic xanthoastrocytoma with anaplasia and BEND5-NTRK2 fusion in a young adult with a history of cranial radiation for childhood rhabdomyosarcoma. Neurooncol Adv. 2025 Mar 8;7(1):vdaf052. doi: 10.1093/noajnl/vdaf052. PMID: 40568680; PMCID: PMC12188291.
- ↑ Martínez, Ramón; et al. (2014-03-20). "DNA methylation alterations in grade II- and anaplastic pleomorphic xanthoastrocytoma". BMC cancer. 14: 213. doi:10.1186/1471-2407-14-213. ISSN 1471-2407. PMC 4000050. PMID 24650279.
- ↑ Tang, Karen; et al. (2020-08-01). "Exploring DNA Methylation for Prognosis and Analyzing the Tumor Microenvironment in Pleomorphic Xanthoastrocytoma". Journal of Neuropathology and Experimental Neurology. 79 (8): 880–890. doi:10.1093/jnen/nlaa051. ISSN 1554-6578. PMC 8453609 Check
|pmc=value (help). PMID 32594172 Check|pmid=value (help). - ↑ https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2024.1268038/full
- ↑ Dampier, Christopher H.; et al. (2025). "Molecular, histologic, and clinical characterization of methylation class pleomorphic xanthoastrocytoma: An analysis of 469 tumors". Neuro-Oncology Advances. 7 (1): vdaf089. doi:10.1093/noajnl/vdaf089. ISSN 2632-2498. PMC 12305539 Check
|pmc=value (help). PMID 40735274 Check|pmid=value (help).
Notes
Khan WA: “Pleomorphic xanthoastrocytoma”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 02/25/2026, https://ccga.io/index.php/CNS5:Pleomorphic xanthoastrocytoma.