Neurooncology Terminology
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What is the characteristic genetic mutation found in Pleomorphic xanthoastrocytoma (PXA)?

  • HRAS p.G13V mutation
  • KRAS p.G12C mutation
  • BRAF p.V600E mutation (correct)
  • NRAS p.Q61R mutation

    • What is the ICD-O coding for Pleomorphic xanthoastrocytoma (PXA)?

  • 9384/3
  • 9424/3 (correct)
  • 9361/3
  • 9400/3

    • What is the typical localization of Pleomorphic xanthoastrocytoma (PXA)?

  • Deep brain structures
  • Spinal cord
  • Infratentorial region
  • Superficial location involving the leptomeninges and cerebrum (correct)

    • What is the most common presenting symptom of Pleomorphic xanthoastrocytoma (PXA)?

    <p>Seizures</p> Signup and view all the answers

    What is the CNS WHO grade of Pleomorphic xanthoastrocytoma (PXA)?

    <p>CNS WHO grade 2 or 3</p> Signup and view all the answers

    What is the characteristic histopathological feature of Pleomorphic xanthoastrocytoma (PXA)?

    <p>numerous eosinophilic granular bodies</p> Signup and view all the answers

    What is the ICD-11 coding for Pleomorphic xanthoastrocytoma (PXA)?

    <p>2A00.0Y &amp; XH99U2</p> Signup and view all the answers

    What is the percentage of Pleomorphic xanthoastrocytoma (PXA) tumours that occur supratentorially?

    <p>98%</p> Signup and view all the answers

    Where is PXA typically located?

    <p>In the cerebral cortex and leptomeninges</p> Signup and view all the answers

    What is the appearance of PXA on CT?

    <p>Hypodense, hyperdense, or mixed</p> Signup and view all the answers

    What is the incidence of PXA?

    <p>Less than 0.3% of primary CNS tumours</p> Signup and view all the answers

    What is the mean age at diagnosis of PXA?

    <p>26.3 years</p> Signup and view all the answers

    What is the frequency of anaplasia in PXA at first diagnosis?

    <p>31% of cases</p> Signup and view all the answers

    What is the proposed origin of PXA?

    <p>Subpial astrocytes</p> Signup and view all the answers

    What genetic alteration is frequently found in PXA?

    <p>BRAF p.V600E mutation</p> Signup and view all the answers

    What is characteristic of PXA histopathology?

    <p>Non-infiltrative growth pattern</p> Signup and view all the answers

    What is often seen in PXA tumour cells?

    <p>Lipid droplets</p> Signup and view all the answers

    What is often seen in the leptomeningeal areas of PXA?

    <p>Reticulin fibres surrounding individual tumour cells</p> Signup and view all the answers

    What is a characteristic feature of Pleomorphic xanthoastrocytoma (PXA)?

    <p>Homozygous CDKN2A and/or CDKN2B deletion</p> Signup and view all the answers

    What is the typical location of Pleomorphic xanthoastrocytoma (PXA)?

    <p>Superficial location involving the leptomeninges and cerebrum</p> Signup and view all the answers

    What is the annual incidence of Pleomorphic xanthoastrocytoma (PXA)?

    <p>Less than 0.7 cases per 100 000 population</p> Signup and view all the answers

    What is the mean age at diagnosis of Pleomorphic xanthoastrocytoma (PXA)?

    <p>26.3 years</p> Signup and view all the answers

    What is a common symptom of Pleomorphic xanthoastrocytoma (PXA)?

    <p>Seizures</p> Signup and view all the answers

    What is a characteristic feature of anaplastic Pleomorphic xanthoastrocytoma (PXA)?

    <p>Brisk mitotic activity</p> Signup and view all the answers

    What is the frequency of anaplasia in Pleomorphic xanthoastrocytoma (PXA) at first diagnosis?

    <p>31% of cases</p> Signup and view all the answers

    What is the prevalence of CNS WHO grade 3 Pleomorphic xanthoastrocytoma (PXA)?

    <p>Unknown</p> Signup and view all the answers

    What is the ICD-O coding for Pleomorphic xanthoastrocytoma (PXA)?

    <p>9424/3</p> Signup and view all the answers

    What is a characteristic feature of PXA on imaging?

    <p>Strong, heterogeneous contrast enhancement</p> Signup and view all the answers

    What percentage of PXAs harbour BRAF p.V600E mutation?

    <p>60-80%</p> Signup and view all the answers

    What is the main differential diagnosis of PXA?

    <p>Ganglioglioma</p> Signup and view all the answers

    What is the frequency of CDKN2A and/or CDKN2B homozygous deletion in PXAs?

    <p>94%</p> Signup and view all the answers

    What is the characteristic of the tumour cells in PXA?

    <p>pleomorphic and spindle-shaped</p> Signup and view all the answers

    What is the molecular pathway commonly altered in PXAs?

    <p>MAPK pathway</p> Signup and view all the answers

    What is the characteristic of the intraoperative smears in PXAs?

    <p>pleomorphic cells with frequent fibrillary processes</p> Signup and view all the answers

    What is the immunophenotype of PXAs?

    <p>GFAP and S100 positive, CD34 positive</p> Signup and view all the answers

    What is the main differential diagnosis of PXA in cases with a dominant population of epithelioid cells?

    <p>Epithelioid glioblastoma</p> Signup and view all the answers

    What is the frequency of NTRK1, NTRK2, and NTRK3 alterations in PXAs?

    <p>less than 10%</p> Signup and view all the answers

    What is the characteristic of the tumour cells in PXAs regarding neurons?

    <p>they do not resemble neurons</p> Signup and view all the answers

    What is the frequency of MAPK pathway gene alterations in PXA?

    <p>High</p> Signup and view all the answers

    Which syndrome is PXA rarely associated with?

    <p>Familial adenomatous polyposis</p> Signup and view all the answers

    What is the proposed origin of PXA?

    <p>Subpial astrocytes</p> Signup and view all the answers

    What is the most common genetic alteration in PXA?

    <p>BRAF p.V600E mutation</p> Signup and view all the answers

    What is a characteristic histopathological feature of PXA?

    <p>Granular bodies</p> Signup and view all the answers

    What is the criteria for CNS WHO grade 3 PXA?

    <p>≥ 2.5 mitoses/mm2</p> Signup and view all the answers

    What is the typical immunophenotype of PXA?

    <p>GFAP positive, S100 positive</p> Signup and view all the answers

    What is the significance of necrosis in PXA?

    <p>It is often seen in tumors with high mitotic activity</p> Signup and view all the answers

    What is the Ki-67 labelling index in CNS WHO grade 3 PXA?

    <p>15%</p> Signup and view all the answers

    What is the macroscopic appearance of PXA?

    <p>Partially cystic, superficial cortical mass</p> Signup and view all the answers

    Which of the following genetic alterations is commonly found in anaplastic tumours?

    <p>TERT promoter mutation</p> Signup and view all the answers

    What is the primary purpose of DNA methylation profiling in PXA?

    <p>To confirm the diagnosis in tumours with ambiguous morphology</p> Signup and view all the answers

    Which of the following tumours has been reported to have a molecular constellation similar to PXA?

    <p>Epithelioid glioblastomas</p> Signup and view all the answers

    What is the significance of the combination of BRAF p.V600E mutation and CDKN2A and/or CDKN2B deletion in PXA?

    <p>It is highly suggestive of a diagnosis of PXA</p> Signup and view all the answers

    Which of the following is a characteristic of PXA on imaging?

    <p>It is frequently cystic and involves the cerebral cortex</p> Signup and view all the answers

    What is the significance of the morphological spectrum of molecularly defined PXA?

    <p>It may be substantially wider than previously thought</p> Signup and view all the answers

    Which of the following is a rare location for PXA?

    <p>Retina</p> Signup and view all the answers

    What is the main purpose of diagnostic molecular pathology in PXA?

    <p>To confirm the diagnosis of PXA</p> Signup and view all the answers

    Which of the following is a characteristic of PXA tumours involving the cerebellum and spinal cord?

    <p>They present with symptoms reflecting these sites of involvement</p> Signup and view all the answers

    What is the significance of the research on the molecular constellation of PXA?

    <p>It has provided insights into the pathogenesis of PXA</p> Signup and view all the answers

    On T1-weighted MRI images, the solid portion of the PXA tumour is typically

    <p>hypointense or isointense to grey matter</p> Signup and view all the answers

    What is the annual incidence of PXA per 100,000 population?

    <p>&lt; 0.7 cases</p> Signup and view all the answers

    In which syndrome have rare cases of PXA been reported?

    <p>DiGeorge syndrome</p> Signup and view all the answers

    What is the most common genetic alteration found in PXA?

    <p>BRAF p.V600E mutation</p> Signup and view all the answers

    What is the typical growth pattern of PXA?

    <p>Solid and non-infiltrative</p> Signup and view all the answers

    Which of the following is a characteristic of PXA histopathology?

    <p>Presence of xanthomatous cells</p> Signup and view all the answers

    What is the significance of subpial astrocytes in PXA?

    <p>They are the cells of origin</p> Signup and view all the answers

    What is the frequency of PXA in male and female patients?

    <p>Equally common in both sexes</p> Signup and view all the answers

    What is the significance of TERT promoter mutations in PXA?

    <p>They are more common in tumours with anaplasia</p> Signup and view all the answers

    What is the macroscopic appearance of PXA?

    <p>Solid, yellow, and partially cystic</p> Signup and view all the answers

    Study Notes

    Definition and Coding

    • Pleomorphic xanthoastrocytoma (PXA) is an astrocytoma with large pleomorphic cells, spindle cells, and lipidized cells, often with eosinophilic granular bodies and reticulin deposition.
    • ICD-O coding: 9424/3
    • ICD-11 coding: 2A00.0Y & XH99U2

    Localization

    • Superficial location involving the leptomeninges and cerebrum is typical.
    • Most tumours (98%) occur supratentorially, often in the temporal lobe.
    • Rare cases have been reported in the cerebellum, spinal cord, and retina.

    Clinical Features

    • Many patients present with a long history of seizures.
    • Cerebellar and spinal cord tumours have symptoms reflecting these sites of involvement.
    • Gross total resection cannot be achieved in cases with deep localization and/or wider infiltration.

    Epidemiology

    • PXA accounts for < 0.3% of primary CNS tumours.
    • Annual incidence: < 0.7 cases per 100,000 population.
    • Occurs equally in male and female patients.
    • Typically develops in children and young adults.
    • Mean age at diagnosis: 26.3 years (median: 20.5 years).

    Etiology

    • No specific etiology is known.
    • PXA may be encountered in patients with neurofibromatosis type 1, DiGeorge syndrome, familial melanoma-astrocytoma syndrome, Down syndrome, and Sturge-Weber syndrome.

    Pathogenesis

    • Proposed to originate from subpial astrocytes.
    • Typically carries alterations in genes encoding members of the MAPK pathway (most frequently BRAF p.V600E mutation) combined with homozygous deletion of the tumour suppressor genes CDKN2A and/or CDKN2B at 9p21.3.
    • May carry TERT promoter mutations or (less frequently) amplifications, more common in tumours with anaplasia.

    Macroscopic Appearance

    • Sometimes yellow (from lipidization), partially cystic, superficial cortical masses.
    • May extend into the adjacent leptomeninges.

    Histopathology

    • Mostly solid, non-infiltrative growth pattern.
    • Composed of a mixture of spindled, epithelioid, pleomorphic, and multinucleated astrocytes.
    • Characterized by intranuclear pseudoinclusions, prominent nucleoli, and lymphocytic infiltration.
    • Granular bodies, both pale and brightly eosinophilic, are characteristic.

    Cytology

    • Intraoperative smears show a variable population of pleomorphic and spindled neoplastic cells with fibrillary processes.
    • Large, bizarre cells with binucleation or trinucleation are common.

    Diagnostic Molecular Pathology

    • MAPK pathway gene alterations (essentially all PXAs).
    • BRAF p.V600E mutation (most frequent, ~60% of cases).
    • CDKN2A and/or CDKN2B homozygous deletion (up to 94% of PXAs).
    • TERT alterations (more common in anaplastic tumours).
    • DNA methylation profiling may be useful in tumours with ambiguous morphology.### Definition and Classification
    • Pleomorphic xanthoastrocytoma (PXA) is an astrocytoma characterized by large pleomorphic cells, spindle cells, and lipidized cells with eosinophilic granular bodies and reticulin deposition.
    • PXA is associated with BRAF p.V600E mutation (or other MAPK pathway gene alterations) and homozygous CDKN2A and/or CDKN2B deletion.
    • ICD-O coding: 9424/3 Pleomorphic xanthoastrocytoma
    • ICD-11 coding: 2A00.0Y & XH99U2 Other specified gliomas of brain & Pleomorphic xanthoastrocytoma

    Localization and Clinical Features

    • PXAs typically occur in a superficial location, involving the leptomeninges and cerebrum (mostly in the temporal lobe).
    • 98% of tumours occur supratentorially, with rare cases in the cerebellum and spinal cord.
    • Patients often present with a long history of seizures.
    • Cerebellar and spinal cord tumours have symptoms reflecting their site of involvement.

    Imaging

    • On imaging, PXA appears peripherally located and often cystic, involving the cerebral cortex and overlying leptomeninges.
    • CT and MRI show variable tumour appearance (hypodense, hyperdense, or mixed) with strong, sometimes heterogeneous, contrast enhancement.

    Epidemiology

    • PXAs account for < 0.3% of primary CNS tumours, with an annual incidence of < 0.7 cases per 100,000 population.
    • The tumour occurs equally in male and female patients, typically affecting children and young adults (mean age at diagnosis: 26.3 years).

    Etiology and Pathogenesis

    • No specific etiology is known, but PXA may be associated with neurofibromatosis type 1, DiGeorge syndrome, familial melanoma-astrocytoma syndrome, Down syndrome, and Sturge-Weber syndrome.
    • PXA originates from subpial astrocytes, which explains the superficial location of most tumours.

    Molecular Features

    • PXAs typically carry alterations in genes encoding members of the MAPK pathway (most frequently BRAF p.V600E mutation) combined with homozygous deletion of the tumour suppressor genes CDKN2A and/or CDKN2B at 9p21.3.
    • Other genetic alterations, such as TERT promoter mutations, SMARCB1, BCOR, BCORL1, ARID1A, ATRX, PTEN, FANCA, FANCD2, FANCI, FANCM, PRKDC, NOTCH2, NOTCH3, NOTCH4, and BCL6, have been described, but their pathogenetic significance is uncertain.

    Macroscopic and Microscopic Appearance

    • PXAs are sometimes yellow (from lipidization), partially cystic, superficial cortical masses, although their gross appearance may be nonspecific.
    • Histopathologically, PXAs demonstrate a mostly solid, non-infiltrative growth pattern, composed of a mixture of spindled, epithelioid, pleomorphic, and multinucleated astrocytes that are sometimes filled with lipid droplets (xanthomatous cells).

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    Description

    This quiz covers the definitions, coding, and related terminology of neurooncology, including ICD-O and ICD-11 coding, clinical features, and diagnostic criteria.

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