HistoPath - Neuro-oncology Flashcards

1
Q

How are brain tumours classified (WHO)

A

Grade 1 - Extra-axial:
- Meningothelial cells – meningioma
- Schwann cells – schwannoma
Grade 2-4 Intra-axial (infiltrate the tissue of the brain):
- Astrocytes – astrocytoma
- Oligodendrocytes – oligodendroglioma
- Ependyma – ependymoma
- Neurons – neurocytoma
- Embryonal cells – medulloblastoma (Children)

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2
Q

How are brain tumours graded

A

via histological criteria (proliferative activity, cell differentiation, necrosis)
Grade I = benign, long-term survival
Grade II = cause death in >5 years (long survival)
Grade III = cause death <5 years (short survival)
Grade IV = cause death <1-year (short survival)

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3
Q

What are the risk factors for CNS tumours

A

Largely unknown
Radiation to head and neck → meningiomas, gliomas
Neurocarcinogens
Genetic predisposition (<5%):
- neurofibromatosis (AutDom)
- Tuberous sclerosis
- Brain tumour polyposis syndrome 1
- Gorlin syndrome
- Von Hippel Lindau

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4
Q

What is the inheritance of neurofibromatosis and what CNS tumours does it predispose to

A

Neurofibromatosis 1 (17q11) → neurofibroma, astrocytoma
Neurofibromatosis 2 (22q12) → schwannoma, meningioma

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5
Q

What are the signs and symptoms of a CNS tumour depending on where it is located

A

Intracranial: headache, vomiting, changed mental state
Supratentorial: focal neurological deficits, seizures, personality change
Subtentorial: cerebellar ataxia, long tract signs, cranial nerve palsies

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6
Q

What investigations should be done for CNS tumours

A

CT/PET-CT
MRI:
- MR-spectroscopy (metabolism)
- Perfusion MRI
- Functional MRI

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7
Q

What is the management for CNS tumours

A
  1. Surgery
    - Craniotomy (debulking)
    - Open biopsy (inoperable but approachable tumour)
    - Stereotactic biopsy (if open biopsy is not indicated)
  2. Radiotherapy (esp gliomas)
  3. Chemotherapy (esp gliomas) - temozolamide
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8
Q

What is the most common primary CNS tumour

A

Glial tumours (diffuse or circumscribed)
Circumscribed:
- Pilocytic astroctomas)
- SEGA
- Pleomorphic xanthoastrocytoma

Diffuse
- Diffuse astrocytoma
- Oligodendroma

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9
Q

Describe diffuse glial tumours

A

High grade, malignant progression
Supratentorial
Adults 20-40yo
IDH1/2 mutation present 30% of cases (+ve prognostic factor)

Astrocytoma (grade 2-4)
Oligodendrogliomas (Grades 2-3)

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10
Q

Describe circumscribed gliomas

A

Low grade, rarely malignant
Posterior fossa
Seen in children
BRAF mutationpresent in 50% of cases (MAPK pathway mutation)

Pilocytic astrocytoma (grade 1)
Ependymomas (usually)
Subependymal giant cell astrocytoma (Grade 1)
Pleomorphic xanthoastrocytoma (grade II)

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11
Q

Describe pilocytic astrocytomas (epidemiology, associations, imaging appearance, histopathology)

A

Most common child brain tumour
Seen in NF1 and with BRAF mutatoins
MRI: cerebellar; well circumscribed, cystic, enhancing
Histopathology:
- Piloid (hairy) cell
- Rosenthal fibres and granular bodies
- Slow growing with low mitotic activity

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12
Q

Describe diffuse astrocytomas (epidemiology, associations, imaging appearance, histopathology)

A

20-40yo
Cerebral hemispheres (adults), cerebellum (children)
IDH1/2 mutation in 80%
MRI: cerebral hemispheres, non-enhancing lesion, low choline:creatinine ratio
Histopathology: negligible/absent mitotic activity, vascular proliferation and necrosis absent

Will eventually become a glioblastoma

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13
Q

Describe glioblastomas (epidemiology, associations, imaging appearance, histopathology, cytology)

A

> 50yo
90% de novo with wildtype IDH, 10% progress from astrocytomas
MRI: heterogenous, enhancing post-contrast
Cytology: high cellularity, high mitotic activity, microvascular proliferation, necrosis
Histo: pathological blood vessels, blood vessel structural abnormalities, cellularity

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14
Q

Describe meningiomas (imaging appearance, histology)

A

Largely benign
MRI: extra-axial, isodense, contrast-enhancing
Histo: attaches to meninges, does not typically invade (displaces brain matter), globules seen

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15
Q

How are meningiomas graded

A

Based on histology (mitotic activity, cell morphology and brain invasion) per 10 HPF

Grade I (80%)= benign, recurrence <25% | <4 mitotic activity

Grade II (20%)= atypical, recurrence 25-50% | 4-20 mitotic activity

Grade III (1%)= malignant, recurrence 50-90% | >20 mitotic activity

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16
Q

What are the most frequent tumours to metastasise to the brain and where are they most commonly found

A

Mets = most frequent CNS tumour in adults)

Breast
Lung
Melanoma

Mets at the grey-white matter junction

17
Q

Describe medulloblastomas

A

Embyronal cell origin - neuroepithelial precursors of the cerebellum/dorsal brainstem
Cerebellum
2nd most common brain tumour in children

18
Q

What is the histology of medulloblastoma

A

“Small blue round cell” tumour (i.e. it is a blastoma/ of a primitive cell line)
Expression of neuronal markers (very little/poorly differentiation) – i.e. synaptophysin, GFAP, Ki67
Homer-Wright rosettes are a feature of primitive neuronal differentiation

19
Q

Which tumours do tuberous sclerosis and Von Hippel lindau predispose to

A

Tuberous sclerosis: haemartoma, SEGA (sub-ependymal giant cell astrocytoma)

Von Hippel lindau: haemangioblastoma

20
Q

Describe oligodendromas

A

20-40yo
MRI; no enhancement
Cytology: fried egg ells (lots of cytoplasma)
Histo: genetic mutation in 100%, esp IDH1/2 co-deletion 1p/19q→ good prognosis