Intracranial Tumours Flashcards
What are the most common CNS tumours?
- Gliomas
- Meningiomas
What structures are involved in gliomas?
Glia cells.
What structure is involved in mimningiomas?
Meninges.
Who is gliomas most common in?
Males.
Who is meningiomas most common in?
Females.
What CNS tumours are common in children?
- Cerebellum
- PNET (primitive neuroectodermal tumour)
- Ependymoma
- Germ cell
Why don’t neurons give rise to many tumours?
Not in direct contact with the blood supply.
What connects neurons to the blood supply?
Glia cells.
What are the 4 types of glia cells?
- Astrocytes
- Oligodendrocytes
- Ependymal cells & choroid plexus cells
- Microglia
What is the function of astrocytes?
Support and protection.
What is the function of oligodendrocytes?
Myelinating cells.
What is the function of ependymal cells & choroid plexus cells?
Produce CSF.
What is the function of microglia?
Defence (resident macrophages in CNS).
What are the 5 main CNS tumours?
- GLIOMA (glia cells)
- MENINGIOMA (meninges)
- NEUROCYTOMA (neuronal)
- PNET (primitive)
- SCHWANNOMA (nerve sheath)
What are the 3 types of glioma?
- Astrocytoma
- Oligodendroglioma
- Ependymoma
How are tumours differentiated histologically?
Name of the tumour.
-e.g. glioblastoma
How are tumours differentiated based on biological behaviour?
Grade of the tumour (how malignant).
-I to IV
What is the biological behaviour of a benign tumour? (4)
- slow growing
- no/slow progression
- respect surrounding tissue
- no recurrence
How are benign tumours treated?
Surgery.
What is the biological behaviour of a malignant tumour? (4)
- fast growing
- progress
- invade surrounding tissue
- recurrent
How are malignant tumours generally treated?
Surgery and adjuvant therapy.
Why can benign tumours in the thalamus/brainstem be fatal?
Almost impossible to remove.
How are tumours graded?
I to IV.
-I = most mild, IV = most severe
What are the characteristics of a grade I tumour?
- Benign
- No recurrence
- No/slow porgression
What are the characteristics of a grade II tumour?
- Low grade
- Some progression
- Astrocytoma (6-7 yr life expectancy)
What are the characteristics of a grade III tumour?
- High grade
- Rapid progession
- Astrocytoma (2-3 yr life expectancy)
What are the characteristics of a grade IV tumour?
-Very agressive
-
What is the histological criterai for a malignancy in brain tumours? (4)
- No stability (cell density & atypia)
- More mitotic activity
- Necrosis (compete for resources)
- Vascular proliferation
What are the microscopic features of astrocytic tumours?
- Microcystic background
- Increased cell density
- Pleomorphism (size/shape)
What are the main features of a diffuse astrocytoma? (4)
- Infiltrative & microcystic
- Fibrillary
- Low cellular density
- Mild atypia
What grade are diffuse astrocytomas normally?
Grade II.
Do diffuse astrocytomas have mitotic activity?
No.
What is the median survival for diffuse astrocytomas?
80 months.
What are the main features of anaplastic astrocytomas? (2)
- Moderate cellular density
- Moderate pleomorphism
Do anaplastic astrocytomas have mitotic activity?
Yes.
What grade are anaplastic astrocytomas normally?
Grade III.
What is the median survival for anaplastic astrocytomas?
30 months.
What are the main features of glioblastomas? (3)
- High cellular density
- Necrosis
- Vascular proliferation
What grade are glioblastomas normally?
Grade IV.
Do glioblastomas have mitotic activity?
Yes - lots.
What is the median survival time for glioblastomas?
10 months.
What are the main features of pilocytic astrocytomas? (6)
- Children
- Cerebellum
- Well defined
- Vascular proliferation
- Cystic
- Rosenthal fibres
What grade are pilocytic astrocytomas normally?
Grade I.
What are the main features of oligodendrogliomas? (3)
- Round nucleus with clear cytoplasm (FRIED EGG)
- Arborising capillaries
- Calcifications
What grade are oligodendrogliomas normally?
Grade II-III.
What are the main features of ependymomas? (4)
- Round uniform cells
- Well-defined tumour
- Pseudorosettes
- Ventricles
What grade are ependymomas normally?
Grade II-III.
What are the main features of meningiomas? (6)
- Females
- Dura
- Well-defined
- Extra-axial tumours
- Whorls
- Psammoma bodies
What grade are meningiomas normally?
Grade I.
What are the main features of PNET - medulloblastomas? (5)
- Children
- Cerebellum
- Very high cellular density
- Anaplastic hyperchromatic cells
- Rosette
What grade are PNET - medulloblastomas normally?
Grade IV.
Do PNET - medulloblastomas have mitotic activity?
Yes, frequent.
Which tumours mainly affect the cerebellum in children? (2)
- PNET - medullblastomas
- Policytic astrocytomas
Which tumours mainly affect females?
Meningiomas.
Which tumours mainly affect males?
Gliomas.
What type of tumour has a median survival rate of 10 months?
Glioblastoma.
What type of tumour cell has a ‘fried egg’ appearance (round nucleus, clear cytoplasm)?
Oligodendroglioma.
What type of tumour contains rosenthal fibres?
Pilocytic astrocytoma.
What is a rosenthal fibre?
A long, thick eosinophlic (pink) bundle seen in some slow growing astrocytomas.
What type of tumour is extra-axial, and where is it found?
Meningioma - in dura.
NB. cannot cross BBB
Name 3 types of nerve sheath tumours.
- Spindle cell tumours
- Schwannoma
- Neurofibroma
What grade are schwannomas and neurofibromas?
Both grade I.
Why can schwannomas be problematic?
They are benign, but can be difficult to remove.
What cranial nerve do schwannomas affect?
Cranial nerve VIII.
Give 2 features of schwannomas.
- BIPHASIC pattern (loose and dense areas)
- RETICULIN fibres (type III colagen)
What structures do neurofibromas affect?
Spinal nerves.
What substance are neurofibromas rich in?
Collagen.
What do signalling pathways normally do?
Regulate self-renewal during stem cell development.
What does the Wnt signalling pathway normally act on? (3)
- Haemopoietic
- Epidermal
- Gut
What tumours form if there is a mutation in the Wnt signalling pathway? (2)
- Colon carcinoma
- Epidermal tumours
What does the Shh signalling pathway normally act on? (3)
- Haemopoietic
- Neural
- Germ line
NB same as Notch
What tumours form if there is a mutation in the Shh signalling pathway?
- Medulloblastoma
- Basal cell carcinoma
What does the Notch signalling pathway normally act on? (3)
- Haemopoietic
- Neural
- Germ line
NB same as Shh
What tumours form if there is a mutation in the Notch signalling pathway?
- Leukaemia
- Mammary tumours
How do astrocytes lead to glioblastoma formation?
Astrocyte
»astrocytoma
»anaplastic astrocytoma
»glioblastoma (2*)
Name 2 possible events that occur to transform astrocytes into astrocytomas.
- Chromosome 17p loss
- TP53 gene mutation
What happens to cause astrocytomas to transform into anaplastic astrocytomas?
Chromosome 19q loss.
Name 2 possible events that occur to transform anaplastic astrocytomas into glioblastomas.
- Chromosome 10q loss
- Hypermethylation of RBI gene
What are the 4 markers that are most relevant for molecular diagnostics of gliomas?
- MGMT promoter methylation
- 1p/10q deletion
- IDH1/IDH2 mutation
- BRAF duplication/fusion
What type of tumour is only affected by MGMT methylation?
Primary glioblastoma.
Grade IV
What type of tumour is only affected by BRAF alteration?
Pliocytic astrocytoma.
Grade I
How do intracranial tumours often present? (5)
- ^ Intracranial pressure
- Epilepsy
- Neurological deficit
- Endocrine dysfunction
- Focal symptoms (e.g. weakness)
What are symptoms of raised intracranial pressure? (3)
- Headaches (morning)
- Vomiting
- Blurred vision
What may cause a raised intracranial pressure? (3)
- Tumour
- Oedema
- Obstructive hydrocephalus
What type of tumour may cause seizures?
Supratentorial.
What are the 5 main types of neurological deficits?
- Cognitive
- Visual
- Cranial nerve
- Motor
- Sensory
What may endocrine dysfunction lead to?
- Over-production
- Under-production
What do haematological investigations often show with intracranial tumours?
Increased haemoglobin.
What tumour markers are tested for? (3)
- aFP
- Bhcg
- PSA
Why are chest x-rays often carried out with suspected intracranial tumours?
To detect 2* tumours.
How are intracranial tumours managed? (3)
- MEDICAL (steroid/anti-convulsants/hormone replacement)
- SURGICAL
- ADJUVANT THERAPY (chemo-/radio- therapy)
What are the 2 surgical options for intracranial tumours?
- Biopsy
- Excision (total/partial)
What is 5-ALA and how is it used for surgery?
A chemical given before surgery»_space; highlights tumour cells.
What are gliadel wafers?
Implants placed in space where tumour was during surgery»_space; chemotherapy to the brain.
What is stereotactic surgery?
Minimally invasive surgery - uses 3D systems to locate the target.
Are meningiomas and schwannomas normally benign or malignant?
Benign.
What are the main effects of steroid treatment?
Decreased swelling, but»_space; weight gain.
What are possible side effects of anti-epileptics?
- Personality changes
- Drug interactions
Which hemisphere is normally dominant?
Left hemisphere.
-i.e. concerned with language
What is radiotherapy?
Use of x-rays to treat tumours.
-CT/MRI used to locate target first
What is proton therapy?
Type of external beam radiotherapy.
-Doesn’t increase chance of cure, but lower doses of radiation»_space; non-target regions
Who is proton therapy predominantly used for?
Children.
What are the acute side effects (days to weeks) of cranial radiotherapy? (3)
- Cerebral oedema (» ^ICP)
- Hair loss
- Scalp/ear erythema
What are the intermediate (weeks to months) side effects of cranial radiotherapy? (1)
Somnolence syndrome (severe tiredness).
What are the late (months to years) effects of cranial radiotherapy?
Damage to sensitive structures»_space; cataracts, hypothyroidism, memory loss.
What are the median survival for the different grades of gliomas?
GRADE 1 : many years
GRADE 2 : 5-12 years
GRADE 3 : 2-4 years
GRADE 4 : 6-18 months
Give 2 examples of CNS tumours that can be cured by treatment.
- Germ cell tumours
- Medulloblastomas
What are the 2 main purposes of chemotherapy?
- Palliative treatment
- Enhance effectiveness of radiotherapy
CASE 1 : fit and 2 week of gradual numbness and weakness on RHS.
-where is the lesion?
Left fronto-parietal region.
What is the left fronto-parietal region often affected by?
Strokes.
-Middle cerebral artery
CASE 2 : woman seems to understand what is said to her, but makes no sense. She is right handed.
-where is the lesion?
Left temporo-frontal region.
-Broca’s area
What speech disorder is caused by damage to the Broca’s area?
Expressive aphasia.
CASE 3 : 50 yr old, beomes withdrawn & bad-tempered, then develops headaches and vomiting.
-where is the lesion?
Frontal regions.
NB can tolerate big pathology before symptoms appear
CASE 4 : 55 yr old, cannot dress herself properly, has numbness down one side and develops headaches.
-where is the lesion?
Parietal lobe.
|»_space;sensory loss, dyspraxia and inattention
