primary CNS neplasms

Question 1

aetilogy f primary brain tumours

Answer 1

sporadic, unknown cause, due to sporadic mutations in key genes
sometimes: ionising radiation, immunodeficiency
some associated with genetic syndrome

Question 2

why are brain tumours staged differently to other sites

Answer 2

they dont tend to metastasise

Question 3

IDH mutant vs. wildtype

Answer 3

mutant has far better survivability

Question 4

what is IDH

Answer 4

isocytrate dehydrgenase

Question 5

diffuse glioma

Answer 5

two categories

• peadiatric type
• adult type

neoplasms of glial cells with a diffuse growth pattern (not well circumcised

Question 6

paediatric type diffuse gliomas

Answer 6

low grade (rare) 
high grade - mostly mutations, more common, still relatively rare, all are WHO grade 4, por prognosis

Question 7

adult type diffuse gliomas

Answer 7

mutatsions in isocitrate dehydrogenase are key drivers in lwer grade gliomas in adults and now are used to define this class of tumours
either IDH mutant or IDH wild type

Question 8

IDH mutant adult diffuse gliomas

Answer 8

slow and im some cases no prgression to higher grades
astrocytic differentiation if they acquire secnd mutations
if they carry translocation of chromosomes this leads to oligodentral differentiation and means better prognosis

Question 9

IDH wild type adult diffuse gliomas

Answer 9

presence of different activating mutation
rapid prgression to grade 4 with relatively rapid acquisition of ther mutations
low grade IDH wild type doesnt meaningfully exist

Question 10

grading of diffuse gliomas in adults

Answer 10

astrocytma, IDH mutant = grade 2-4
glioblastoma, IDH wildtype = grade 4

molecular testing is required to tell the difference between the two

Question 11

location of astrocytomas and oligodendromas

Answer 11

any regins on the CNS, most commonly supretentorial, frontal lob/frontotemporal region more common site

Question 12

presentation of astrocytomas and oligodendromas

Answer 12

gradually proggressive headache, subtle and progressive neurological abnormalities
memory/cognitive/speech/language/motor/sensory/persnality/behaviour

Question 13

IDH wildtype tumours more likely to present with

Answer 13

seizures or collapse

Question 14

low grade diffuse astrocytomas

Answer 14

6-9 years survival
usually supratentorial cerebral hemispheres
solid +/- cystic, diffuse - firm and tough, infiltrative, ill-defined, may crss midline via corpus collosum

Question 15

grade 3 diffuse astrocytoma

Answer 15

2-3 years average survival
macroscopically no distinguishing features from grade 2
microscopically, more cellular, more nuclear atypia, mitotic activity

Question 16

high grade astrocytoma/glioblastoma

Answer 16

15-20% of intracranial gliomas
peak incidence 45-55 years
very poor prognosis - rapidly fatal, especially if IDH wildtype, but treatment options can be effective (surgury + chemotherapy + radiotherapy)

Question 17

macroscopic appearance of high grade astrocytoma/glioblastoma

Answer 17

large infiltrative tumur, necrosis, heterogenous appearance, cystic change, heamorrhage

Question 18

histology if high grade astrocytoma/glioblastoma

Answer 18

astrocytic differentiation, pleomorphis, with areas of divergent differentiation in some cases, mitoses, vascular proliferation, necrosis

Question 19

oligodendroglioma IHD mutant

Answer 19

have IDH mutatins
who grade 2 if conventional hitology
if high grade hstological features are present then grade 3
- young to middle aged
- insidious onset (presentation ooften with seizures)
- grow slowly
- preferentially involve superficial regions of cerebral hemispheres

prognosis is significantly better than for astrocytoma
average survival >10 years

Question 20

combined 1p 19q deletions

Answer 20

strong predictor of response to chemotherapy and radiotherapy and overall survoval in both low and high grade ligodendrogliomas
definitional mutation: presence = oligodendroma

Question 21

pilocystic astrocytoma

Answer 21

circumscribed asstrocytoma
children and young adults
10 year survival >95%, usually treated by surgery alone
piloid astrocytes (long hari like processes) that tend to result in formation of roosenthal fibres and oesinophilic granular bodies

Question 22

meningioma

Answer 22

10-20% primary intracranial tumours also common around spinal cord
mean age late 50s
F:M 2:1
distribution parallels arachnoid villi

Question 23

sequelae of meningioma

Answer 23

can compress brain/cord parenchyma; usually not brain invasive
may invade bone, sinuses, dura, cause reactive hyperostosis and/or bony erosion with invasion

Question 24

meningioma histological features

Answer 24

whorls (groups of cells radiating from a central cluster) 
syncytial arrangements (cells fuse and cant see cell mambranes) 
bland ovoid nuclei 
nucelar psuedoinclusions

Question 25

meningioma behaviour

Answer 25

there is grade 1-3, no grade 4
grading based on mitotic activity, presence of brain invasion and/or cellular anaplasia
recurrence- free + overall survival determined by a number of factors (histoloogical subtype, differentiation, resectability, brain invasion)

Question 26

medulloblastoma

Answer 26

paediatric and adult
common in paediatric, rare in adults)
WHO grade 4 but better prognosis than paediatric WHO grade 4 astrcytoma as better response to treatment
primitive looking cells with neuroectodermal differentiation, may have nodular areas that are better differentiated

Question 27

schwannoma

Answer 27

tumour of perineural cells around peripheral nerves
10% intracranial neoplasms
other cranial nerves, spinal - dorsal roots, peripheral nerves
firm, solid, sometimes cystic
WHO grade 1

Question 28

accoustic neuroma

Answer 28

specific subtype of schwanoma
airises from VIII cranial nerve at cerebelloopontine angle that are usually solid, however are often bilateral in neurofibromatosis