Histo: Neuro-Oncology Flashcards
(35 cards)
How much more common are secondary brain tumours than primary brain tumours?
10x more
Describe the radiological classification of brain tumours.
- Extra-axial (coverings) - tumours of the bone, meninges and metastatic deposits
- Intra-axial (parenchyma) - derived from normal cell populations of the CNS (e.g. glia, neurones, vessels) or derived from other cell types (e.g. lymphomas, metastases)
List the different cell types within the CNS that can give rise to brain tumours.
neurons, glial cells (astrocytes, oligodendrocytes, ependymal cells, and microglia), choroid plexus cells, cells related to blood vessels and coverings.
What is the most common genetic syndrome associated with brain tumours?
Neurofibromatosis
What is the inheritance pattern of neurofibromatosis?
Autosomal dominant
Where are the genes that cause neurofibromatosis located?
- NF1 = 17q11
- NF2 = 22q12
List some manifestations of brain tumours that are:
- Supratentorial
- Subtentorial
and what are they referring to when you say tentorial?
-
Supratentorial
- Focal neurological defect
- Seizures
- Personality changes
-
Subtentorial
- Cerebellar ataxia
- Long tract signs
- Cranial nerve palsy
Tentorial - tentorium cerebelli
Outline the management options for brain tumours.
- Surgery - aim for maximal safe resection with minimal damage to the patient. Debulking may be performed and biopsies may be taken.
- Radiotherapy - used for gliomas and metastases
- Chemotherapy - mainly for high-grade gliomas
What is the WHO classification of brain tumours based on?
- Tumour type (cell of origin) e.g. astrocyte or oligodendrocyte
- Tumour differentiation (grading) (tells you how long they are gonna live)
NOTE: metastases are not graded
Outline the meaning of the different WHO grades for brain tumours.
- Grade I = benign, long-term survival
- Grade II = death in > 5 years
- Grade III = death in < 5 years
- Grade IV = death in < 1 years
NOTE: grades I and II are low
Which brain tumours are staged?
None
Except medulloblastoma
What is the most common type of primary brain tumour?
Glial tumours
List some key features of pilocytic astrocytomas.
- Usually grade I
- Mainly occurs in children
- Associated with NF1
- Often cerebellar
- BRAF mutation in 70% of cases
What is the hallmark histological feature of pilocytic astrocytoma?
- Piloid (hairy) cell
- Often see Rosenthal fibres and granular bodies
- Slow-growing with low mitotic activity
List some key features of astrocytoma.
- Usually Grade II-IV
- Cerebral hemispheres are the most common site in adults
- Can progress to become a higher grade (malignant progression)
- IDH2 mutation in 80% of cases
- Mitotic activity and vascular proliferation is absent
What can astrocytomas eventually become?
Glioblastoma (after 5-7 years)
List some key features of glioblastoma multiforme.
- Grade IV
- Most patients > 50 years
- High cellularity and high mitotic activity
- Microvascular proliferation and necrosis
What does glioblastoma multiforme tend to arise from?
90% arise de novo and have wildtype IDH
10% occur secondary to astrocytoma and have IDH mutation
What is a characteristic histological feature of oligodendroglioma?
Round cells with clear cytoplasm (friend egg)
List some key features of meningioma.
- Mainly low grade (I and II)
- Can be multiple (e.g. in NF2)
- Can cause focal symptoms (e.g. seizures, compression)
Which histological feature of meningioma is important in determining grade?
Mitotic activity (number of mitoses per 10 high power fields)
- Grade 1: < 4
- Grade 2: 4-20
- Grade 3: > 20
NOTE: brain invasion is also an important thing to assess (presence of brain invasion makes it grade II)
How does grade of meningioma affect the management options?
Grade II and III requires radiotherapy as well as surgery
What is a medulloblastoma?
- Embryonal tumour originating from neuroepithelial precurosrs of the cerebellum and dorsal brainstem
- They are always found in the cerebellum
Which tumours most commonly metastasise to the brain?
- Lung
- Breast
- Melanoma
