CNS tumors

Question 1

what is the most common type of intracranial tumour

Answer 1

those of neuroepithelial origin (glial cells - astrocytes and oligodenrocytes) - that being astocytoma (glioma)

Question 2

what is WHO classification of gliomas

Answer 2

grades I and II are benign and common in children
grades III is called anaplastic astrocytoma
grade IV is called glioblastoma multiforme, it is most commonly detected and is the most malignant grade

Question 3

what are the mechanisms by which you can get glioblastoma multiforme

Answer 3

increasing mutations which can occur directly from a grade I neoplasm (progressive pathway) or directly from a precursor cell (de novo pathway)

Question 4

glioblastoma multiforme appearance on imaging

Answer 4

peripheral enhancement which is irregular
a central necrotic core which does not enhance with contrast
there is also surrounding oedema

it travels along white matter tracts, it can cross the corpus callosum, and can give an appearance similar to B cell lymphoma

Question 5

what is the aetiology of brain tumours

Answer 5

largely unknown
factors that have increased predisposition:
- previous head injury
- carcinogen exposure
- immunosuppression
- ionising radiation exposure (former tinea capitis Tx)
- small hereditary component

Question 6

Meningiomas

Answer 6

are benign tumours of the arachnoidal cells and can occur anywhere along the dura

it is infrequently detected, more common in females, and more common in the elderly

Question 7

CNS metasis

Answer 7

common for:
- lung cancer
- breast cancer
- renal cancer
- colon cancer
and malignant melanoma

there are usually multiple metastatic lesions, which are ring enhancing, and are subcortical with vasogenic oedema

Question 8

Presenting signs of brain tumours

Answer 8

• vomiting and nausea
• headaches (worse supine, and you wake up with the headache)
• focal neurological signs (from mass effect)
• drowsiness

Question 9

Pituitary adenomas

Answer 9

are associated with optic chiasm compression and Px with

• bitemporal hemianopia
• opthalmoplegias or oculomotor palsies

Question 10

What are the most common pituitary adenoma

Answer 10

Prolactinoma - gynaecomastia
GH-oma - produce acromegaly facies

most are null-omas (produce no hormone)

Question 11

Common cranial and peripheral nerve tumours

Answer 11

• Schwannoma

- Neurofibroma

Question 12

Contrast between neurofibromas and schwannomas

Answer 12

Schwannomas are benign and present later in life, are more common in females

Neurofibromas are more common than Schwannomas, contain a mixed cell type, and are difficult to excise

Question 13

The who familial neurofibromas are

Answer 13

type I - has widespread cafe au lait spots (chromosome 17)

type II - is rarer - usually acoustic neuromas (benign)

Question 14

Paediatric CNS tumours are second to leukaemia what are they

Answer 14

70% are in the posterior fossae or the infratentorium

most common is - medulloblastoma - embryonic origin
next common -pilocytic astrocytoma is common is associated with a benign cystic mass within the cranial cavity

Question 15

What genetic disorder predisposes you to CNS neoplasia

Answer 15

von Hipple Lindau Syndrome (very rare)

Question 16

Neurons are

Answer 16

the functional cells of the nervous system and are classed primarily on shape

Question 17

Glial cells are

Answer 17

These cells outnumber the neurons of the body and are actively dividing (unlike neurons), and are regarded as neuron supporting cells, because of their active cell division they are privy to neoplastic transformation

they include

• astrocytes (which control the local environment of the neuron)
• microglia - which are the macrophages of the neurons, absorb debris and are at sites of injury
• oligodendrocytes - make up CNS myelin
• Schwann cells - make up PNS myelin