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YR5 Histopathology > Neurooncology > Flashcards

Neurooncology Flashcards

1
Q

What are the classifications of primary CNS tumours based on location?

A

EXTRA-AXIAL (COVERINGS):

Tumours of bone, cranial soft tissue, meninges, nerves

Majority BENIGN

INTRA-AXIAL (PARENCHYMA):

From normal cell populations of the CNS e.g. glia, neurons, neuroendocrine cells. Or from other cell types lymphomas, germ cell tumours.

INFILTRATIVE

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2
Q

What are more common CNS tumours?

A

Non-malignant tumours are more common than malignant tumours

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3
Q

What is the aetiology of CNS tumours?

A

Radiotherapy to head + neck: meningiomas, rarely gliomas.

Genetics: < 5% of primary brain tumours- Familial syndromes

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4
Q

What is the chromosome and loci for NF1 and NF2?

A

NF1: 17q11

NF2: 22q12

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5
Q

Give 5 familial CNS tumour syndromes

A

Neurofibromatosis 1: Neurofibroma, Astrocytoma

Neurofibromatosis 2: Schwannoma, Meningioma

Brain Tumour Polyposis: Malignant gliomas

Gorlin: Medulloblastoma

Von Hippel Lindau: Hemangioblastoma

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6
Q

What are signs and symptoms of CNS tumours?

A

Intracranial HTN:

Headache + vomiting

Change in mental status

Supratentorial: (cerebral hemispheres)

Focal neurological deficit

Seizures

Personality changes (frontal lobe)

Infratentorial:

Cerebellar Ataxia

Long tract signs (motor descending, sensory ascending)

CN palsy

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7
Q

What is the most common type of CNS tumour in adults?

A

Metastatic CNS tumour

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8
Q

What is the most common type of CNS tumour in children?

A

Pilocytic astrocytoma

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9
Q

What are the management options for CNS tumours?

A

SURGERY:

Max. safe resection with min. damage to patient

Gives best outcome (depends on age + performance status)

Resectability: location, size, no. lesions

RADIOTHERAPY:

Low + high-grade gliomas, mets, selected benign tumours

External fractionated RT, stereotactic radiosurgery

CHEMO:

High-grade gliomas (temozolomide) + lymphomas

Biological agents (EGFR inhibitors, PD-L1 inhibitors)

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10
Q

What are the diagnostic and therapeutic objectives for CNS tumour surgery?

A

Craniotomy for debulking: Subtotal + complete resections (as much tumour as poss).

Open biopsy: Inoperable but approachable tumours (~1cm), usually representative.

Stereotactic biopsy: If open biopsy not indicated (~0.5cm tissue), tissue may be insufficient for dx.

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11
Q

What is histopathology and molecular pathology of tissue biopsy used for in CNS tumours?

A

To provide a definitive + complete dx.

To guide tx: Predictive tests assays for target therapy.

To assess tx response.

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12
Q

What is the WHO classification of CNS tumours based upon?

A

Tumour type: Putative cell of origin or lineage of differentiation.

Tumour grade: Aggressiveness.

Molecular profile: Most tumour types have molecular markers.

NO TNM STAGING

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13
Q

What is tumour typing for CNS tumours?

A

Tumour type: Histological type

Defined by histological features

Tumour names derived from putative cell of origin

Histological type predicts tumour behaviour.

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14
Q

What is the grading system in CNS tumours?

A

Attempt to stratify tumours by outcome i.e. degree of malignancy.

Based on morphological criteria of malignancy (proliferative activity, cell differentiation, necrosis) + increasingly on genetic profile.

Based on predicted natural clinical behaviour + does not consider response to tx: many pts with treated high-grade tumours have longer survival than expected according to grade.

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15
Q

What are the 4 grades according to the WHO classification?

A

G1: Benign: long-term survival

G2: > 5y

G3: < 5y

G4: < 1y

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16
Q

What are tumour grades used for?

A

To guide tx

17
Q

Give 4 characteristics of diffuse gliomas. Name 2 diffuse gliomas.

A

Grades ≥ 2

Adults

Supratentorial

Malignant progression.

Astrocytomas (G 2-4)

Oligodendrogliomas (G 2-3)

18
Q

Give 4 characteristic features of circumscribed gliomas. Name 3 examples.

A

Grades 1-2

Children

Often posterior fossa

Rare malignant transformation

Pilocytic astrocytoma (G1)

Subependymal giant cell astrocytoma (G1)

Ependymomas (usually circumscribed)

19
Q

Which mutations are associated with diffuse gliomas?

A

IDH1/2 mutations (30%)

20
Q

Describe the epidemiology and site of pilocytic astrocytomas.

Describe the features on MRI, histology, genetics.

A

Usually 1st + 2nd decade

Account for 20% of CNS tumours <14y

Often cerebellar, optic-hypothalamic, brainstem.

MRI: Well circumscribed, cystic, enhancing lesion.

Histology: Piloid “hairy” cell. Very often Rosenthal fibres.

Slow growing: Low mitotic activity

Genetic profile: BRAF mutation in 70%

21
Q

What are the features of diffuse gliomas?

A

Usually 20-40y

Astrocytomas + Oligodendrogliomas

+/- Pathogenic point mutation in IDH1/2

IDH mutation A/W longer survival + better response to chemo + radiotherapy.

22
Q

Describe the epidemiology and site of astrocytomas. Describe the features on MRI, histology, genetics.

A

20-40y

Cerebral hemispheres.

MRI: T1 hypointense, T2 hyperintense, non-enhancing lesion. Low choline/ creatinine ratio at MRSpec.

Histology: Low to moderate cellularity. Mitotic activity is low. No vascular proliferation/ necrosis.

Genetic profile: +/- Point mutation in IDH1/2.

23
Q

What is the rule of progression in astrocytomas?

A

Progress from grade 2 to 3 to 4, typically in <10y

24
Q

What is glioblastoma multiforme?

A

Most aggressive + most frequent glioma

Cerebral hemispheres affected

Incidence ↑ with age, most >50y

Median survival: 8m

25
Q

What are signs on investigation for glioblastoma multiforme?

A

MRI: Heterogeneous, enhancing post-contrast.

Histology: High cellularity + neoangiogenesis, necrosis.

Genetic profile: IDH1 wildtype.

Common mutations in TERT, PTEN, EGFR

26
Q

What is this? What can be seen?

A

Glioblastoma multiforme

High cellularity

(normal brain tissue at top)

27
Q

What is this? What can be seen?

A

Glioblastoma multiforme

Neoangiogenesis (microvascular proliferation)

28
Q

Describe the epidemiology of meningioma. From which cells do they arise? What is seen on MRI?

A

38% of primary CNS tumours.

Rare in < 40y

Incidence ↑ with age.

Originate from meningothelial cells of Arachnoid mater, at any site of craniospinal axis

Can be multiple (NF2).

MRI: Extraxial, isodense, contrast-enhancing.

29
Q

What is the distribution of WHO grades for meningiomas?

A

80% G1: Benign, recurrence < 25%

20% G2: Atypical, recurrence 25-50%

1% G3: Malignant, recurrence 50-90%

30
Q

Why is subtyping and grading useful for meningiomas?

A

Grading = most useful predictor of recurrence.

Mainly based on histology, recently molecular markers (ex TERT mutation, methylome)

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

15 morphological subtypes across 3 grades.

31
Q

What are CNS metastases?

A

Most frequent CNS tumour in adults (10 x intrinsic tumours).

Increasing incidence due to longer survival.

Often multiple, located at grey/white matter junction +/- leptomeningeal disease.

May be 1st presentation of the disease.

Origin can be challenging to determine: immunohistochemical markers.

Very poor prognosis.

32
Q

What are the most common cancers to give rise to CNS metastases?

A

Any cancer can give CNS mets

Most frequently:

Lung ca

Breast ca

Melanoma

Renal cell ca

Can use antibodies to detect primary site.

33
Q

What are medulloblastomas?

A

WHO Grade 4.

EMBRYONAL TUMOUR: Originates from neuroepithelial cells/ neuronal precursors of the cerebellum or dorsal brainstem.

RARE but 2nd most common brain malignancy in children + YA.

Outcome considerably improved with radio-chemotherapy + subtype stratification.

34
Q

Describe the epidemiology of CNS tumours

A

Mets 10x more frequent than primary

Primary rare in adults, most common tumour in children

Extra-axial tend to be benign

Intra-axial infiltrate, tend to be malignant

35
Q

Name the tumour based on the putative cell of origin

Astrocytes

Oligodendrocytes

Ependyma

Neurons

Embryonal cells

Meningothelial cells

Schwann cells

A

Astrocytes: Astrocytoma

Oligodendrocytes: Oligodendroglioma

Ependyma: Ependymoma

Neurons: Neurocytoma

Embryonal cells: Medulloblastoma

Meningothelial cells: Meningioma

Schwann cells: Schwannoma, Neurofibroma

36
Q

Describe tumours of the nervous system based on central or peripheral distribution

A

CNS: Brain + coverings, spinal cord + coverings, pituitary

PNS: small nerves in any organ (neurofibromas of skin/ soft tissue) + large nerves (cranial + spinal nerve schwannomas)

Most peripheral are benign

37
Q

How is mitotic activity useful?

A

Determines grade

Mitosis per 10 HPF

<4 = G1

4-20 = G2

>20 = G3

38
Q

What is the methylome profile?

A

Characteristic patterns of DNA methylation of CpG islands

Epigenetic profile

Stable signature, reflects cell of origin

Helpful for atypical cases, rare entities, small biopsies, sub-typing

YR5 Histopathology (27 decks)

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