CNS tumours

Question 1

How are brain tumours classified (WHO)

Answer 1

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)

Question 2

What are the risk factors for CNS tumours

Answer 2

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

Question 3

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

Answer 3

Autosomal dominant
Neurofibromatosis 1 → neurofibroma, astrocytoma
Neurofibromatosis 2→ schwannoma, meningioma

Question 4

Symptoms and signs of CNS tumours

Answer 4

Headache: worse in the morning/leaning forward/coughing
Persistent or recurrent vomiting
Problems with balance, coordination or walking
Behavioural changes
Abnormal eye movements or changes in vision
Seizures (without fever)
Abnormal head position- wry neck, head tilt or persistent stiff neck

RICP
Papilloedema
Cushing’s triad

Question 5

Symptoms and signs of CNS tumours according to location

Answer 5

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

Question 6

Investigations for CNS tumours

Answer 6

MRI head
- MR-spectroscopy (metabolism)
- Perfusion MRI
- functional-MRI
CT head/PET-CT
LP: ?mets in CSF

Question 7

Management for CNS tumours

Answer 7

MDT
SURGERY
- maximal safe resection to obtain and extensive excision with minimal damage to the patient
- Resectability is dependent on the location, site and number of lesions
- Craniotomy → debulking (subtotal and complete resections)
- Open biopsies → inoperable but approachable tumours
- Stereotactic biopsy → open biopsy not indicated
Radiotherapy and chemotherapy
The use of this varies with tumour type and the age of the patient

Question 8

Prognosis for CNS tumours

Answer 8

Grade I = benign, long-term survival LOW grade, LONG survival
Grade II = cause death in >5 years LOW grade, LONG survival
Grade III = cause death <5 years HIGH grade, SHORT survival
Grade IV = cause death <1-year HIGH grade, SHORT survival

Question 9

What is the most common primary CNS tumour

Answer 9

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

Diffuse
- Diffuse astrocytoma
- Oligodendroma

Question 10

Describe diffuse glial tumours

Answer 10

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)

Question 11

Describe circumscribed gliomas

Answer 11

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)

Question 12

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

Answer 12

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

Question 13

Describe diffuse astrocytomas (epidemiology, associations, imaging appearance)

Answer 13

20-40yo
Cerebral hemispheres (adults), cerebellum (children)
IDH1/2 mutation in 80%
MRI: cerebral hemispheres, non-enhancing lesion, low choline:creatinine ratio

Will eventually become a glioblastoma

Question 14

Describe glioblastomas (epidemiology, imaging appearance)

Answer 14

> 50yo, most common primary tumour in adults
MRI: solid tumours with central necrosis and a rim that enhances with contrast.

Question 15

Describe meningiomas (epidemiology, location, imaging appearance, histology)

Answer 15

Second most common primary brain tumour in adults
Largely benign
Arises from the dura mater, seen in the falx cerrebri/superior sagittal sinus
MRI: extra-axial, isodense, contrast-enhancing
Histo: attaches to meninges, does not typically invade (displaces brain matter), globules seen, psammoma bodies

Question 16

Describe medulloblastomas (origin, location, epidemiology, histology)

Answer 16

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

Histo: small blue round cell, neuronal markers, homer-wright rosettes

Question 17

Which tumours do tuberous sclerosis and Von Hippel lindau predispose to

Answer 17

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

Von Hippel lindau: haemangioblastoma

Question 18

Describe oligodendromas (epidemiology, imaging apperance, histology)

Answer 18

20-40yo
MRI; no enhancement
Histology: fried egg ells (lots of cytoplasm)

Question 19

Describe craniopharyngioma (epidemiology, origin, symptoms)

Answer 19

Most common paediatric supratentorial tumour
Tumour arising from Rathke pouch
S/S: hormonal disturbance, symptoms of hydrocephalus or bitemporal hemianopia.