High grade gliomas Flashcards
What percentage of gliomas to astrocytomas account for?
33% of all gliomas
What percentage of CNS tumours do astrocytomas account for?
7-10%
What are most astrocytomas graded as?
1-4
What are grade 3 and 4 astrocytomas visually?
Almost indistinguishable
What are grade 1 astrocytomas labelled as?
Pilocytic
What age do group grade 1 (pilocytic) astrocytomas arise?
Children and young adults
Where do grade 1 (pilocytic) astrocytomas mainly arise?
Posterior fossa
What is the behaviour of grade 1 (pilocytic) astrocytomas?
Slow growing - may stop or regress
What is the grade 1 (pilocytic) astrocytoma survival percentage?
80-90%
What improves grade 1 (pilocytic) astrocytoma prognosis?
Complete resection improves prognosis. Recent understanding of the biology of the tumour means that there may be alternative biological therapies.
What are other sites of grade 1 (pilocytic) astrocytoma other than posterior fossa?
Cerebrum, optic nerve and chiasm, thalamus and basal ganglia brain stem and spinal cord (occasionally SCF)
What do the majority of grade 1 (pilocytic) astrocytoma tumours never become?
They never become less well differentiated and more malignant
What are grade 2 astrocytomas labelled as?
Diffuse
What age do group grade 2 (diffuse) astrocytomas arise?
Young adults
Where do grade 2 (diffuse) astrocytomas mainly arise?
Cerebrum, brain stem and spinal cord
How do grade 2 (diffuse) astrocytomas present?
As seizures
What is the median postoperative survival of grade 2 (diffuse) astrocytomas?
5-8 years
What do grade 2 (diffuse) astrocytomas evolve to be?
Malignant
What role do RT and chemo have in the management of grade 2 (diffuse) astrocytomas?
Controversial
What are grade 3 astrocytomas labelled as?
Anaplastic (“diffusely infiltrating”)
What age do group grade 3 (anaplastic) astrocytomas arise?
Middle age
What is the median postoperative survival of grade 3 (anaplastic) astrocytomas?
2-4 years although there are people who can live much longer
What do grade 4 (anaplastic) astrocytomas evolve to be?
Almost always fatal. At the later stages it is thought to transform to glioblastoma.
What are grade 4 astrocytomas labelled as?
IDH mutant
What were grade 4 (IDH Mutant) astrocytomas labelled as prior to the WHO classification of CNS tumours 2021?
Considered Glioblastoma prior to the ‘WHO classification of CNS tumours -5th Ed (2021)
Classification changed based on the presence of IDH mutation – Glioblastoma now considered separate entity.
What age do group grade 4 (IDH Mutant) astrocytomas arise?
Generally younger presentation than glioblastoma
What is the male:female ratio of grade 4 (IDH Mutant) astrocytomas?
M:F around 1.5
What is the management of grade 4 (IDH Mutant) astrocytomas?
The same as glioblastoma
What is the survival in years of grade 4 (IDH Mutant) astrocytoma?
5 year survival – 3.6 yrs. – better than glioblastoma
What percentage of pre-WHO 5th Ed of cases would’ve been classified as glioblastoma?
Around 10% of pre-WHO 5th Ed of cases=G4 IDH Mutant (would have been classified as glioblastoma prior to this)
What are grade 4 glioblastomas labelled as?
IDH-Wildtype
What age do grade 4 (IDH Wildtype) glioblastomas arise?
Any age but most common in those 70 +
Where do grade 4 (IDH Wildtype) glioblastomas mainly arise?
Cerebrum
Basal ganglia
Rarely arises in the cerebellum
A small percentage cross corpus callosum when it is described as the “butterfly tumour”
How does grade 4 (IDH Wildtype) appear?
Macroscopic appearance – grey mass with areas of haemorrhaging, yellow necrosis and sometimes cysts.
Appear to have a capsule – this is an artefact of rapidly growing tumour and compressed brain.
Adjacent brain is swollen and oedematous
Spreads along white matter tracts..
Migratory cells are found many cm from the main body of the tumour
Tumour appears to be multi-focal but are actually from one site
Microvascular proliferation and necrosis are the hallmarks of glioblastoma.
Glioblastoma is recognisable radiologically
What is glioblastoma (IDH Wildtype) in terms of malignancy?
Most malignant form of glioma. It is poorly differentiated and highly invasive. It has areas of necrosis and microvascular proliferation
Diffuse astrocytic tumour
Necrosis
Microvascular proliferation
EGFR gene amplification
Formed de novo.
What does MGMT stand for?
Methylguanine DNA Methyltransferase
What are the advantages of MGMT Methylation Promotor?
Generally longer survival than those without MGMT methylation promotion
Positively impacts the efficacy of Temozolomide
?Offer temozolomide to patients without promotion
What are the advantages of Isocitrate Dehydrogenase - IDH1 & 2 Gene Mutations?
Patients whose tumours express IDH mutations have improved survival compared to wild-type IDH
90% Wild-Type
Tumour formed as a Glioblastoma from the beginning
10% Mutated
Tumour was previously a lower grade tumour
What does IDH stand for?
Isocitrate Dehydrogenase
What are the 3 forms of glioblastoma?
Giant cell glioblastoma
Gliosarcoma
Epithelioid glioblastoma
Who does glioblastoma most likely occur?
Occurs in older people
No prior history of tumour
Poor prognosis
How does glioblastoma appear?
Grey masses
Areas of haemorrhage
Yellow necrosis
Cysts
Never encapsulated (appear to have capsule – this is an artefact of rapidly growing tumour and compressed brain)
Tissue adjacent to tumour oedematous
Oedema located around white matter
Offers a route for satellite cells to migrate from the main body of the tumour
This can make the tumour appear multifocal
What is the management of glioblastoma?
Biopsy to confirm diagnosis
Removal of maximum volume of tumour possible (maximal safe resection (MSR)
Radiotherapy
Chemotherapy (TMZ)
What does WHO grade oligodendroglioma as?
Grade 2
What percentage are oligodendrogliomas?
5-10%
What is the peak age for oligodendrogliomas?
30-50 years old
Where do oligodendrogliomas arise?
Arise in white matter:
Frontal, parietal and temporal lobes
occasionally arises in the spinal cord
Very rarely arises in the cerebellum
How do oligodendrogliomas present?
Slow growing
Patient often describes long history of seizures.
CT, MRI and Plain skull x-rays often reveal calcification (~50% cases)
Long standing tumours may cross corpus callosum – even when low grade
Unlike glioblastoma – occasionally high grade oligodendroglioma can do unaccountably well
How do oligodendrogliomas appear on a CT?
Often areas of calcification evident
Do oligodendrogliomas respond to chemo?
Yes – PVC (procarbazine, lomustine, vincristine)
