Neuro-oncology Flashcards
What are primary CNS tumours
originated in CNS
most common (vs secondary) in children
what are secondary CNS tumours
mets
10x more common than primary tumours
(30% of patients with systemic cancer develop CNS metastases)
what are extra-axial CNS tumours (coverings)
Tumours of bone, cranial soft tissue, meninges, nerves
less malignant than intra-axial
what are intra-axial CNS tumours (parenchyma)
from normal cell populations of the CNS - flia, neurons and neuroendocrine cells
form other cell types - lymphomas, germ cell tumours
more malignant - WHO grade 2-4 - Infiltrate the tissue of the brain – not encapsulated and they invade the brain tissue
aetiology of CNS tumours
unknown
env - radiotherapy to head and neck -> meningioma (and rarely glioma)
genetic predisposition <5% primary - familial syndromes
what are familial CNS tumour syndromes - with examples
Autosomal dominant inheritance with frequent de novo mutations
signs and symptoms for CNS tumours
subtle in slow growing // short hx for malignant
intracranial HTN - SOL - headache, vomiting, change in mental status
supratentorial - focal neuro deficit, seizures, personality change (frontal lobe)
infratentorial - cerebellar ataxia, long tract signs (brain stem: motor/sensory tracts), cranial nerve palsy (ocular signs)
imaging modalities used for CNS tumours
CT-scan
MR-scan – more usual in more chronic
MR-spectroscopy (metabolism)
Perfusion MRI
Functional MRI
PET-scan – more research looking for particular ligand binding
Use of imaging in CNS tumours
Assess tumour type
Guide resection & biopsy
Assess post-surgery – have you taken all tumour
Assess response to treatments
Follow-up recurrence and progression
mx for cns tumour - surgery
max safe resection with min damage to normal
need margin of normal - might be limited depending on where is in brain
resection - location, size, nymber of lesions
mx of CNS tumours - radiotherapy
low and high grade glioma
metastases
some benign
external fractionated radiotherapy, stereotactic radiosurgery
mx of cns tumours - chemo
high-grade gliomas (temozolomide – mixed effectiveness) and lymphomas
Biological agents (EGFR inhibitors, PD-L1 inhibitors, etc.)
when is craniotomy used for CNS tumours
for debulking
may be sub-total or complete resections - depending where is
remove as much tumour as possible
When is open biopsy used for CNS tumours
for inoperable but approachable tumours - 1cm of tissue
usually representative - able to make dx
when is stereotactic biopsy used for CNS tumours
if open biopsy not indicated (about 0.5cm of tissue)
tissue may be insufficient esp if heterogenous - might not get definitive dx
why do we need tissue dx of cns tumour
for:
* definitive and complete dx
* prognostic and predictive tests
* assessment of treatment response
Histopathology can make a decision while patient is on the table
what is a pilocystic adenoma
Who grade 1
intraparenchymal tumour
infra-tentoral, posterior fossa
usually 1st and 2nd decade of life - children
20% CNS tumours below 14 yrs - common
cerebellar, optic-hypothalamus, brainstem
BRAF mutation in 70%
MRI - well circumscribed, cystic, enhancing lesion
Pilocystic astrocytoma histology
Piloid “hairy” cells
Very often Rosenthal fibres – blue arrow
Slowly growing, low mitotic activity
What is astrocytoma
WHO grade 2-4
pts 20-40yrs
cerebral hemispheres
point mutation - IDH1/2
summarise glioblastoma multiforme
who grade 4
Most aggressive and most frequent glioma
incidence increase with age, most >50yrs
median survival - 8mo
Histology of glioblastoma multiforme
High cellularity
Neoangiogenesis – overdeveloped
Necrosis
Not clean margin – tumour invading the tissue of the brain
what are meningiomas
WHO grade 1-3
38% primary CNS tumours
rare less 40yrs - increases with age
Originate from meningothelial cells of the arachnoid mater
Any site of craniospinal axis, can be multiple (NF2)
more accessible to neurosurgeons - good surgery outcomes
MRI: extraxial, iso-dense, contrast-enhancing, well circumscribed - not invading parenchyma
how is mitotic activity used to determine grade
Hyperintense nuclear material
Count them per high power field
Grade depending on how many mitotic bodies find
Mitosis per 10HPF (0.16mm2)
<4 = grade 1
4-20 = grade 2
>20 = grade 3
why do you have to check the interface between meningoma and cortex
Most are sitting between tissue – but have to make sure not invading (even microinvasion)
summarise CNS mets
most common CNS tumour
incidence increasing because of longer survival.
Often multiple, located at grey/white matter junction and/or leptomeningeal disease
can be 1st disease presentation - hard to know origin, use immunohistochem
poor px because in the brain parenchyma
what is a medulloblastoma
WHO grade 4
embryonal tumour
from neuroepithelial cells/neuronal precursors of the cerebellum or dorsal brainstem
rare
common type in children
outcome improved with radio-chemo and subtype stratification
histology of medulloblastoma
High grade poorly differentiated
Highly proliferated type of tumour
4 histological subtypes: classic, nodular/desmoplastic, extensive nodularity, large cell anaplastic
3 molecular subtypes by transcriptome or methylome profiling: WNT-activated, SHH-activated, nonWNT/nonSHH
