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PathY5 > Neuro oncology > Flashcards

Neuro oncology Flashcards

1
Q

What’s the difference between a primary and secondary CNS tumour?

A

PRIMARY Tumours that originated within the CNS

SECONDARY (Metastases): 10x more frequent than primary tumours in adults

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2
Q

How common are CNS tumours?

A

Primary CNS tumours are rare in adults (1-2%)
Second most common cancer in children (25%)

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3
Q

What is the classification of CNS tumours by location?

A

EXTRA-AXIAL (COVERINGS)
Tumours of bone, cranial soft tissue, meninges and nerves

INTRA-AXIAL (PARENCHYMA)

Derived from the major normal cell populations of the CNS glia, neurons, vessels, connective tissue..

Derived from other cells types metastases, lymphomas (same name as extra-CNS tumours), germ cell tumours

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4
Q

What is the classification of CNS tumours by histology?

A

Neurons
Astrocytes
Oligodendrocytes
Ependyma
Choroid plexus epithelium
Meningothelial cells
Embryonal cells

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5
Q

What genes predispose to CNS tumours?

A

Neurofibromatosis 1 (17q11)
Neurofibromatosis 2 (22q12)
Tuberous Sclerosis 1 (9q34)
Tuberous Sclerosis 2 (16p13)
Turcot’s syndrome (APC 5q21) (PMS2 7p22) (MHL1 Chr3 & 2 Chr2)
Li-Fraumeni (p53 17p13)
Cowden syndrome PTEN (10q23.3)
Gorlin syndrome PTCH1 (9q31)
Von Hippel Lindau (3q25)

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6
Q

How may CNS tumours be inherited?

A

<5% of primary BT
Autosomal dominant inheritance
Clinical/family history
Adequate genetic screening
Surveillance and early diagnosis
NF1: NEUROFIBROMA, PILOCYTIC ASTROCYTOMA
NF2: SCHWANNOMA, MENINGIOMA
TS: HAMARTOMAS, SEGA
VHL: HEMANGIOBLASTOMA

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7
Q

What are the supratentorial S/S of CNS tumours?

A

Focal neurological deficit
Seizure
Headache
Change in mental status
Personality changes

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8
Q

What are the subtentorial S/S of CNS tumours?

A

Cerebellar Ataxia
Long tract signs
Cranial nerve palsy

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9
Q

What imaging can you use for CNS tumours?

How do you use these?

A

CT-SCAN
MR-SCAN

PET-SCAN (tracer compounds - research)

Multiparametric MRI:
MR-SPECTROSCOPY (metabolism)
Perfusion MRI
Functional MRI

Assess tumour type
Guide resection and biopsies
Assess post-surgery
Assess response to treatment
Follow up recurrence and progression

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10
Q

What is the management of a CNS tumours?

A

A. SURGERY
Maximal safe resection aims to obtain an extensive excision
with minimal damage to the patient

Age and performance status
Resectability: location, size, number of lesions
Histology (intraoperative diagnosis)

B. RADIOTHERAPY
Fractionated RT, stereotactic radiosurgery, whole brain

C. CHEMOTHERAPY
Mainly for high-grade gliomas (temozolomide)

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11
Q

What happens in neurosurgery?

A

Stereotactic biopsy – inoperable tumours (about 0.5cm tissue) – tissue may not be representative

Open biopsy – inoperable but approachable tumours (about 1cm) – more accurate

Craniotomy for debulking (as much tissue as possible)

  • To provide a definitive and complete diagnosis
  • To guide treatment: predictive tests assays for target therapy
  • To assess treatment response
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12
Q

What is the WHO classification of CNS tumours?

A
  • Tumour type: putative cell of origin or lineage of differentiation
  • Tumour grade: tumour aggressiveness
  • Molecular profile: expanded compared to previous 4th edition (genetics, methylome), most tumour types have molecular markers

INTEGRATED HISTOLOGICAL AND

MOLECULAR DIAGNOSIS

•No staging (TNM)
(exception: medulloblastoma)

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13
Q

How are tumours named?

A

Descriptive: tumour defined by histology

Names derive from putative cell of origin

Tumour type = histological type

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14
Q

What is grading?

A

The grading system is an attempt to stratify tumours by outcome:

“ Degree of malignancy”
It is based on histopathological criteria (proliferative activity, differentiation, necrosis, genetic profile)

It is based on their natural history = Grading does not consider tumour morbidity/ response to treatment (difference between “biological” and “clinical” outcome)

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15
Q

What is WHO grading?

A

Low Grade (longer survival)

  • Grade I - Long-term survival / cured
  • Grade II - Cause death in more than 5 yrs

High Grade (shorter survival)

  • Grade III - Cause death within 5 yrs
  • Grade IV - Cause death within 1yr

Grading less accurate than typing: limited by size of biopsies
Some tumour types have only one possible grade, some have 2 or 3
Evolving concept

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16
Q

What are glial tumours?

A

Diffuse infiltration - grades ≥ II
- adults
Astrocytoma (grades II-IV)
Oligodendroglioma (grades II-III)

Compressive margins - grades I-II
- children
- rare malignant transformation
Pilocytic astrocytoma (grade I)
Pleomorphic xantoastrocytoma
Subependymal astrocytoma
Ganglioglioma

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17
Q

What are the genetics of glial tumours?

A

DIFFUSE GLIOMAS- IDH mutations (IDJ 1/2 mutations- 30%, H3-1%)

CIRCUMSCRIBED GLIOMAS- MAPK pathway mutations (BRAF, NF1, FGFR)

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18
Q

What is pilocytic astrocytoma?

A

Usually 1st and 2nd decade - 20% of CNS tumours below 14 years

Often cerebellar, optic-hypothalamic, brain stem

MRI: always contrast enhancement and circumscribed
(never diffuse infiltration)

Hallmark: Piloid “hairy” cell
Very often Rosenthal fibres and granular bodies
Slowly growing: low mitotic activity

Genetic profile: BRAF mutation (KIAA1549-BRAF fusion) in 70% of PA

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19
Q

What is this?

A
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20
Q

What are diffuse gliomas?

A
  • ASTROCYTOMA, IDH MUTANT
  • OLIGODENDROGLIOMA, IDH MUTANT

Patients usually 20-40 years

Pathogenic point mutation in the IDH1/2 gene

IDH mutation is associated with longer survival and a better response to

chemotherapy and radiotherapy

Cerebral hemispheres most common site

Progression to higher grade is the rule: astrocytomas become eventually glioblastoma (in 5-7 years)

Most aggressive and most frequent: de novo glioblastoma (grade IV), IDH wildtype

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21
Q

What is a diffuse astrocytoma?

A
  • Occur more commonly between 20-40 years
  • MRI: T1 hypointense, T2 hyperintense, non-enhancing lesion.

Low choline / creatinine ratio at MRSpec.

•Low to moderate cellularity.

Mitotic activity is negligible or absent.

Vascular proliferation and necrosis are absent

Genetic: Mutation of IDH1/2: WHO Definition “A diffuse infiltrating astrocytoma with a mutation in the IDH1 or IDH2 gene”

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22
Q

What is this?

A

Diffuse Astrocytoma

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23
Q

What is glioblastoma multiforme?

A

Most aggressive and common glioma which increases with age (Med survival 8mo)

  • Most patients >50 years
  • MRI: T1 enhancing post-contrast
  • High cellularity and high mitotic activity

Endothelial proliferation and/or necrosis

•90% de novo GBM

IDH wildtype

•10% secondary GBM (progression)

IDH mutant

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24
Q

What is this?

A

Neoangiogenesis and high cellularity

25
Q

What is an oligodendroglioma?

A
  • 5% of all primary brain tumours
  • Patients usually 20-40 years
  • Presents with long history of neurological signs – seizure
  • MRI: no or patchy contrast enhancement; MRI and MRSpec are not predictive of transformation
  • Round cells with clear cytoplasm (fried eggs)
  • Mutation of IDH1/2 + codeletion 1p/19q: “a diffusely infiltrating, slow growing glioma with IDH1/2 mutation and 1p/19q codeletion”

Better prognosis than astrocytomas

Slow growth – resection is important

Better response to chemo and radiotherapy

26
Q

What is this?

A

What is an oligodendroglioma?

27
Q

What is the most frequent brain tumour in adults?

A

Mets (Secondary)

28
Q

What is the most frequent brain tumour in children?

A

Pilocytic astrocytoma

29
Q

What is the major change in the last (2016) CNS tumour classification?

A

f

30
Q

What does tumour grade tell us?

A

v

31
Q

What is a meningioma?

A

•25-30% primary intracranial tumours – second after gliomas

Incidental in up to 10% of post-mortem

  • Rare in patients < 40
  • Any site of craniospinal axis
  • Focal symptoms (seizure, compression)
  • MRI: extraxial, isodense, contrast-enhancing
  • 80% Grade I: benign, recurrence <25%

20% Grade II: atypical, recurrence 25-50%

1% Grade III: malignant, recurrence 50-90%

32
Q

What is this?

A

Meningioma

33
Q

What are the histology and grading criteria?

A
34
Q

Why is mitotic activity important?

A
  • Crucial: determines grade
  • Time consuming: cases must be thoroughly examined (even 100 fields or more)

•

•

mitoses / 10HPF (0.16mm2):

<4 = grade I

4-20 = grade II

> 20 = grade III

35
Q

What is brain invasion?

A
36
Q

What is a (grade IV) Medulloblastoma?

A
  • EMBRYONAL TUMOUR: originates from neuroepithelial precursors of the cerebellum/dorsal brainstem
  • Rare (2 per 1,000,000 year), but second most common brain tumour in children
  • “Small blue round cell tumour”
  • Molecular classification: WNT-activated, SHH-activated,

non-WNT/non-SHH

•Outcome considerably improved with radio-chemotherapy

37
Q

What is this?

A

Medulloblastoma

38
Q

What are CNS Mets?

A
  • Most frequent CNS tumour (10 x intrinsic tumours)
  • Increasing incidence due to longer survival
  • Often multiple
  • Any tumour can potentially give CNS metastases,

may be the first presentation of the disease

  • Most frequent tumours are: lung ca, melanoma, breast ca, renal ca and colon ca.
  • Origin can be challenging to determine
  • Very poor prognosis
39
Q

What is this?

A

Metastases

40
Q
  • 45 year old female
  • History: pulmonary lobectomy
  • 2 days of headache and vomiting
  • Worsening headache
  • CT: right frontoparietal SOL with minimal midline shift to the left

Dd: primary tumour, metastasis, abscess

Diagnosis?

A

f

41
Q

70 year old male

Seizure following 2 weeks of left arm and leg weakness

MRI showing heterogeneous enhancing right frontal lesion, started on steroids

Partial response to steroids with improved dexterity of the left arm and leg

Diagnosis?

A

f

42
Q

What is this?

A

f

43
Q
A
44
Q

Malignant tumours are less common but are often extra axial

A

Malignant tumours are less common but are often extra axial

45
Q

What are the S/S of intercranial HTN?

A

Headache, vomiting

Change in mental status

46
Q

What is tumour type?

A

Tumour type = histological type

Tumour defined by histological features

Tumour names often derive from putative cell of origin or differentiation

Histological type predicts tumour behaviour

47
Q

What is a meningioma?

A
  • 38% of primary CNS tumours
  • Rare in patients < 40, incidence ↑ with age
  • Originate from meningothelial cells of the arachnoid mater.

Any site of craniospinal axis, can be multiple (NF2)

  • MRI: extraxial, isodense, contrast-enhancing
  • 80% Grade 1: benign, recurrence <25%

20% Grade 2: atypical, recurrence 25-50%

1% Grade 3: malignant, recurrence 50-90%

48
Q
A
49
Q

What does this show?

A

Psammoma bodies: calcifications

(Meningioma)

50
Q

What is subtype and grading?

A

Grading is the most useful predictor of recurrence. It is mainly based on histology, recently molecular markers (ex TERT mutation, methylome)

Complex histological assessment: proliferation, cell morphology, microscopic brain invasion…

15 morphological subtypes, 3 grades

51
Q

What is mitotic activity?

A

Crucial: determines grade

mitoses / 10HPF (of 0.16mm2):

<4 = grade 1

4-20 = grade 2

> 20 = grade 3

52
Q

What is microscopic brain invasion?

A

Interface between tumour and cortex should be carefully examined

53
Q

What is a methylome profile?

A
  • Most tumours have characteristic patterns of DNA methylation of CpG islands
  • The methylation signature is stable and reflects the tumour cell of origin or early transformed cells

-> Gives information on tumour type not progression/grade

•The DNA methylation status of a subset of CpG islands is assessed with DNA arrays and compared to a reference dataset (“Classifier”)

54
Q

What is methylation classifier?

A

Helpful for atypical cases, rare entities, small biopsies, and subtyping: ex medulloblastoma subtypes, meningiomas…

Not used for grade/progression or targeted therapy

True molecular classification: does not consider the histology

55
Q

What does the tumour grade tell us?

A

survival

56
Q

Which mutation identifies diffuse astrocytic tumours with a better prognosis?

A

IDH mutation

57
Q

45F headache, previous lobectomy, CT shows frontal lesion and this histology:

A

Metastases

58
Q

5 yr old, headache, vomiting, papilloedema. MRI shows cystic cerebellar lesion, histology:

A

Pilocytic astrocytoma

59
Q

70 yo left arm and leg weakness, seizures. MRI shows heterogenous enhancing right frontal region with this histology:

A

Glioblastoma

PathY5 (98 decks)

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