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YEAR 5: HISTOPATH > Histo: Neuro-Oncology > Flashcards

Histo: Neuro-Oncology Flashcards

1
Q

How much more common are secondary brain tumours than primary brain tumours?

A

10x more

In kids, primary CNS tumours are the most common

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2
Q

Describe the radiological classification of brain tumours.

A
  • Extra-axial (coverings) - tumours of the bone, meninges and metastatic deposits
  • Intra-axial (parenchyma) - derived from normal cell populations of the CNS (e.g. glia, neurones, vessels) or derived from other cell types (e.g. lymphomas, metastases)
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3
Q

List the different cell types within the CNS that can give rise to brain tumours.

A
  • Neurons -
  • Astrocytes
  • Oligodendrocytes - oligodendroglioma
  • Ependyma
  • Choroid plexus epithelium
  • Meningothelial cells
  • Embryonal cells
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4
Q

What is the most common genetic syndrome associated with brain tumours?

A

Neurofibromatosis

syndromes are responsible for <5% primary CNS tumours

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5
Q

What is the inheritance pattern of neurofibromatosis?

A

Autosomal dominant

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6
Q

Where are the genes that cause neurofibromatosis located?

A
  • NF1 = 17q11
  • neurofibroma, astrocytoma
  • NF2 = 22q12
  • schwannoma,meningioma
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7
Q

List some manifestations of brain tumours that are:

  1. Supratentorial
  2. Infratentorial
A
  1. Supratentorial - affecting cortex
    • Focal neurological defect
    • Seizures
    • Personality changes - frontal lobe especially
  2. Infratentorial - affecting cerebellum
    • Cerebellar ataxia
    • Long tract signs - motor problems
    • Cranial nerve palsy

Raised ICP - headache, vomiting, altered mental status

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8
Q

Outline the management options for brain tumours.

A
  • Surgery - aim for maximal safe resection with minimal damage to the patient. Debulking may be performed and biopsies may be taken.
  • Radiotherapy - used for gliomas and metastases
  • Chemotherapy - mainly for high-grade gliomas (temozolomide) and lymphomas
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9
Q

What is the WHO classification of brain tumours based on?

A
  • Tumour type (cell of origin)
  • Tumour grading (proliferation, cell differentiation, necrosis)
  • Molecular markers

NOTE: metastases are not graded

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10
Q

Outline the meaning of the different WHO grades for brain tumours.

A
  • Grade I = benign, long-term survival
  • Grade II = death in > 5 years
  • Grade III = death in < 5 years
  • Grade IV = death in < 1 years

NOTE: grades I and II are low

Grades guide treatment of patients

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11
Q

Which brain tumours are staged?

A

None

Except medulloblastoma

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12
Q

What is the most common type of primary brain tumour?

A

Glial tumours

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13
Q

How are the types of glial tumours seen in children and adults different?

A
  • Diffuse infiltration - mainly seen in adults, become more malignant with time, can either be astrocytomas or oligodendrogliomas
  • Circumscribe gliomas - mainly seen in children, tend to be low-grade, rarely undergo malignant transformation
    e.g. pilocytic astrocytoma
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14
Q

Which genetic mutations are associated with gliomas in adults and in children?

A
  • Diffuse gliomas (adults) - IDH1/2
  • Circumscribed gliomas (children) - MAPK (BRAF)
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15
Q

List some examples of circumscribe gliomas.

A
  • Pilocytic astrocytoma (MOST COMMON)
  • Pleiomorphic xanthoastrocytoma
  • Subependymal giant cell astrocytoma
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16
Q

List some key features of pilocytic astrocytomas.

A
  • Usually grade I
  • Mainly occurs in children
  • Associated with NF1
  • Often cerebellar
  • BRAF mutation in 70% of cases
17
Q

What is the hallmark histological feature of pilocytic astrocytoma?

A
  • Piloid (hairy) cell
  • Often see Rosenthal fibres and granular bodies
  • Slow-growing with low mitotic activity
18
Q

List some key features of astrocytoma.

A
  • Usually Grade II-IV
  • Cerebral hemispheres are the most common site in adults
  • Can progress to become a higher grade (malignant progression)
  • IDH2 mutation in 80% of cases
  • Mitotic activity and vascular proliferation is absent
19
Q

What can astrocytomas eventually become?

A

Glioblastoma (after 5-7 years)

20
Q

What is the most aggressive and most common type of glioblastoma

A

*Glioblastoma multiforme (stage IV)

21
Q

List some key features of glioblastoma multiforme.

A
  • Grade IV
  • Most patients > 50 years
  • High cellularity and high mitotic activity
  • Microvascular proliferation and necrosis
22
Q

What does glioblastoma multiforme tend to arise from?

A

90% arise de novo and have wildtype IDH

10% occur secondary to astrocytoma and have IDH mutation

23
Q

List some key features of oligodendrogliomas.

A
  • Grade II-III
  • Tends to present with a long history of neurological signs (usually seizures)
  • Slow-growing
  • Better prognosis than astrocytoma (better response to chemotherapy and radiotherapy)
24
Q

What is a characteristic histological feature of oligodendroglioma?

A

Round cells with clear cytoplasm (friend egg)

25
Q

Which gene mutations are associated with oligodendroglioma?

A

IDH1/2

Co-deletion of 1p/19q

26
Q

What is the second most common primary intracranial tumour after gliomas?

A

Meningioma

27
Q

List some key features of meningioma.

A
  • Mainly low grade (I and II)
  • Low recurrence afte surgery
  • Can be multiple (e.g. in NF2)
  • Can cause focal symptoms (e.g. seizures, compression)
28
Q

Which histological feature of meningioma is important in determining grade?

A

Mitotic activity (number of mitoses per 10 high power fields)

  • Grade 1: < 4
  • Grade 2: 4-20
  • Grade 3: > 20

NOTE: brain invasion is also an important thing to assess (presence of brain invasion makes it grade II)

29
Q

How does grade of meningioma affect the management options?

A

Grade II and III requires radiotherapy as well as surgery

30
Q

What is a medulloblastoma?

A
  • Embryonal tumour originating from neuroepithelial precursors of the cerebellum and dorsal brainstem
  • They are always found in the cerebellum
31
Q

Describe the histological appearnce of medulloblastoma.

A

Small blue round cell tumour with expression of neuronal markers (very little differentiation)

NOTE: snaptophysin is an example of a neuronal marker

32
Q

What histological feature is suggestive of partial neuronal differentiation?

A

Homer-Wright rosettes

33
Q

Outline the molecular classification of medulloblastoma.

A
  • WNT-associated
  • SHH-associatd
  • Non-WNT/non-SHH
34
Q

Which tumours most commonly metastasise to the brain?

A
  • Lung
  • Breast
  • Melanoma
  • Renal Cell
35
Q

Where in the brain do metastases tend to be found?

A
  • At the grey-white matter junction and/or leptomeningeal
  • This is because the cerebral blood vessels become smaller as they enter the white matter so neoplastic emboli get caught here

Most common CNS tumor

36
Q

How can the DNA methylation of a CNS be useful

A

Gives information on tumour type, not on progression or grade

Good for very rare tumours

YEAR 5: HISTOPATH (20 decks)

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