Tumours

Question 1

5 year recurrence rates of meningiomas based upon Simpson grading

Answer 1

10% for grade 1
20% for grade 2
30% for grade 3
40% for grade 4.

Question 2

Origin of lateral ventricle meningiomas

Answer 2

arachnoid cap cells, also located in choroid plexus.

During embryology, the meningocytes also migrate with choroid plexus, therefore meningiomas can arise from choroid plexus.

Question 3

Prognosis of IDH-wt GBM with GTR vs subtotal resection

Answer 3

41% PFS at 6 months vs
21%.

Question 4

Overall survival of patients with MGMT methylation vs those without MGMT methylation

Answer 4

MGMT methylation: 24 months
no MGMT methylation: 12 months.

Question 5

Histological subtypes of medulloblastomas

Answer 5

CDE A

Classic
Desmoplastic/nodular
Extensive nodularity
Anaplastic/large cell (this would be classified as high risk)

Desmoplastic has best prognosis, most likely to occur in older children

Question 6

Locations of different types of medulloblastomas.

Answer 6

wnt activated tumours develop from WNT expressing cells in the lower rhombic lip.
These tumours are more likely to be located in the cerebellar peduncle/CPA.
SHH – develop from SHH modulated cerebellar cortex. More likely hemispheric.
Group 3 and 4 origin is unclear. But more likely to be located in the fourth ventricle.

Question 7

Features of high risk medulloblastoma, over standard risk

Answer 7

Less than 3y/o
Residual of more than 1.5cm3
Mets

C-myc amplification
>3y/o with anaplastic histology

40% PFS at 5 years with high risk medulloblastomas.

Question 8

Standard risk medulloblastoma treatment and prognosis

Answer 8

craniospinal irradiation (23.4Gy) within 40days of a surgery. Post fossa boost of 55Gf), with concurrent PACKER regime chemotherapy. Once weekly, cisplastin, vincristine, CCNU. 5 year PFS of 80%.

Question 9

Radiosensitive brain tumours

Answer 9

Germinomas, NGGCT
Medulloblastomas and PNETs
DNET
ATRT
Choroid plexus carcinoma

Question 10

ATRT

Answer 10

rhabdoid cells (rod-shaped)
eosinophilic cytoplasm.

Rapid growth, therefore can present with macrocephaly in babies.

Median survival 17 months. (1 year old, death by knife)

Sometimes present with macrocephaly, under 2y/o.
If less than 3 years old, 15% of malignant brain tumours is ATRT, and half arise from post fossa.

Question 11

New feature about astrocytomas in 2021 WHO tumour guidelines

Answer 11

IDH-1 GBM are now classified as grade 4 astrocytomas.

Grade 4 astrocytomas are differentiated from Grades 2 and 3 by the presence of CDKNA2A/B deletion.

Question 12

What does ATRX do

Answer 12

deposits histones at telomeres. Reduced ATRX (ie. ATRX loss) is associated with longer telomeres, a feature of many cancers.

Question 13

Diagnostic features of grade 4 astrocytomas

Answer 13

Necrosis on histology
Or
CDKNA2A/B deleted

Question 14

Low vs high copy number variation of CDKNA2A/B, vs deleted CDKNA2A/B

Answer 14

Low = low grade
High = higher grade astrocytoma
Deleted = grade 4 astrocytoma

Question 15

What is mutually exclusive from IDH in GBM

Answer 15

TERT

If TERT is present in GBM, most likely wild type.
If IDH present in GBM, most likely high grade astrocytoma

Question 16

5 year survival for juvenile pilocytic astrocytomas, according to extent of resection

Answer 16

GTR: >90% 5 year survival
subtotal resection: 50% 5 year survival.

Question 17

What to do with residual pilocytic astrocytoma tumour

Answer 17

See whether can resect more
Active surveillance
Redo resection if there is regrowth
SRS

Question 19

New drug in treatment of IDH gliomas

Answer 19

Vorasidenib.
IDH inhibitor, prevents accumulation of 2HG that leads do tumour growth and progression..

Given in residual or recurrent grade 2 IDHmutant gliomas

Improves radiological PFS from 11 to 28 months

Higher adverse events in vorasidenib group, raised ALT, but was reversible

Question 20

What is Ki67

Answer 20

Proliferative index.
A protein which is present during all active phases of the cell cycle, but not G0

Question 21

Colloid cyst risk score

Answer 21

5 points in total, yes and no

<2 is low risk. >4 is high risk of hydrocephalus

Risk zone = anterior to mammillary bodies or behind aqueduct