Nervous System Tumours

Question 1

Describe medulloblastoma

Answer 1

• Embryonal tumour
• Grade IV malignant tumour (high grade)
• Arises from external granular layer in the cerebellum
• On histology: small round blue cells, homer wright rosettes, mitotically active
• Located in the cerebellum
• Can metastasis in the CNS
• Well circumscribed

Question 2

List gliomas

Answer 2

Astrocytomas

• Pliocytic
• Diffuse
• Anaplastic
• Glioblastoma

Oligodendromas
Ependymomas

Question 3

List meningeal tumours

Answer 3

Meningiomas

Question 4

List peripheral tumours

Answer 4

• Neurofibromas

- Schwannomas

Question 5

Describe pilocytic astocytomas

Answer 5

• Grade 1
• Prominant in children
• Solid nodule with a cystic component on imaging
• Common in the cerebellum, hypothlamus, optic nerve
• Well circumscribed
• Rosenthal fibres, eosinophilic granular bodies on histology
• BRAF mutation

Question 6

Diffuse astrocytomas and anaplastic astrocytoma

Answer 6

Diffuse
- Grade II
- Diffuse
- Most common in cerebral hemispheres
- On histo hypercellular
 No 1p19p codeletion
- Operation recommended before it becomes malignant

Anaplastic

• Grade III
• Diffuse
• Cerebral hemispheres
• Hypercellular, increased mitotic activity
• No 1p19p codeletion

Question 7

Describe glioblastoma

Answer 7

• Grade IV malignant tumour
• Diffuse, infiltrative mass
• Cerebral hemispheres
• Ring enhancement on imaging, internal necrosis
• Histo: hypercellular, increased mitotic activity, microvascular proliferation, necrotizing, pseudopalisading
• EGFR and PTEN mutations

Question 8

Describe oligodendrogliomas

Answer 8

• Grade II-III
• Cerebral hemispheres
• Histo: hypercellular, perinuclear halo (fried egg), negative for astrocyte markers
• 1p19q co deletions

Question 9

Describe ependymomas

Answer 9

• Grade II-II malignant tumour
• Common in cerebellum and spinal cord
• Well circumscribed (non-diffuse)
• Can drop metastases to seed the CSF
• Histo: perivascular and ependymal rosettes

Question 10

Describe meningiomas

Answer 10

• Grade 1
• Adults
• More common in females (possible due to progesterone/oestrogen receptors)
• Dural tails, extra axial location
• Can invade bone and brain
• Histo: cellular whorls, psammoma bodies (calcium deposits)

Question 11

Describe neurofibromas

Answer 11

• Neurofibromatosis type 1 (cafe au lait spots, lisch nodules in the eye)
• Histo: shredded carrot appearance of collagen strands

Question 12

Describe schwannomas

Answer 12

• NF2 association
• Histo: verocay bodies (palisading cells surrounding an acellular zone), biphasic neoplasm with antoni A (hypercellular) and antoni B (hypocellular) regions
• Common: vestibular schwannoma (aka. acoustic neuroma) from CN VIII. Causes hearing problems and disequillibrium

Question 13

Brain tumours: incidence, survival and aetiology

Answer 13

• Malignant tumours 2% of all cancers in adults
• 4400 newly diagnosed each year
• Overall incidence 7 per 100000 population
• 86% gliomas
• Highest rates in developed countries
• Most common over 30, drops at age 72
• 1.5:1 male to female ratio
• Women are more likely to get meningiomas
• Increasing incidence over time
• Survival dependent on age, histologic subtype and grade. Has improved over the past 30 years, but only 30% survive 1 year in 1986-90
• More affluent area=more lively to survive
• 13% five year survival in men and 16% in women in the UK, lower than US
• Second most commoncancer in children, 15-25% childhood malignancies
• Survival for children in UK has increased by 16% since 1971, and is higher than adults (59%)
• Risk factors: genetics (NF for example), ionising radiation, mobile phones (NOT A RISK), low frequency magnetic fields (NOT A RISK), immune factors (viruses, allergies, infections (WEAK), chemicals (n-nitroso compounds? Aspartame? tobacco smoke?), head trauma (recall bias?)

Question 14

Describe neuroimaging used in brain malignancy

Answer 14

• CT scan (used to quickly see what is going on - quick)
• MRI/fMRI
• MR spectroscopy (secondary)
• PET-SCAN (research)

Allows you to:

• Assess tumour type
• Guide resection
• Guide biopsies
• Assess response to treatment
• Assess recurrences

Question 15

Describe treatment of brain tumour

Answer 15

Targeted on the specific case:

• Watch and wait – Incidentally found tumours, benign appearances
• Surgery (stereotactic biopsy in inoperable tumours, open biopsy in inoperable but approachable tumours, and craniotomy for debulking)
• Radiotherapy
• Chemotherapy
• Combination of all of the above – Malignant tumours

Question 16

Describe post-op treatment

Answer 16

• Conventional fractionated radiotherapy
• Chemotherapy (Temozolomide)
• Gamma knife
• Proton beam
• Steroids (usually pre-op)
• Anti-angiogenic factors (Avastin)
• Drugs to control symptoms

Question 17

Describe classification of CNS tumours

Answer 17

Intra-axial – they are located inside the CNS (brain or spinal cord)

Extra-axial – they are located inside the CNS
Primary – they arise from CNS

Secondary – from another organ (metastasis)

Cell of origin

Grades - prognostic value

Question 18

Describe the concept of grading

Answer 18

• There is no staging system for CNS cancer (apart from medulloblastoma)
• The grading system is an attempt to stratify tumours by outcome
• It is based on their natural history
• It is based on histopathological criteria
• Grading does not consider tumour morbidity (difference between “biological” and “clinical” outcome)
• Evolving concept

Grades:

• Long-term survival / cured – Grade I
• Cause death in more than 5 years – Grade II
• Cause death within 5 years – Grade III
• Cause death within 6 mo-1year – Grade IV