Lecture 2 Flashcards
What is the epidemiology of intracranial tumours?
10-17 per 100,000
What is the epidemiology of intraspinal tumours?
1-2 per 100,000
about __ - __% are primary tumors – the rest are metastases from other organs
50 – 75
brain tumours Account for __% of all childhood cancers
20
__% of childhood CNS tumors arise in the posterior fossa
70
__% of CNS tumours tend to arise above the tentorium cerebelli in adults
70
What can a slow-growing, well-differentiated tumour in the brain cause?
- Compression or destruction of smaller, critical brain areas such as the medulla
- Tumours that are difficult to isolate from normal brain tissue can result in extensive destruction when they are removed
- Damage to the blood-brain barrier or development of epilepsy due to the tumour or its removal
T/F: Aggressive, poorly differentiated brain tumours are among the deadliest of cancers
True
What are the most common types of gliomas?
astrocytomas
What are tumours of the higher-grade (IV) going to exhibit?
- greater anaplasia
- greater invasion into the surrounding tissue
- Increased necrosis and more sites of hemorrhage/BBB incompetence
__ = abnormal cellular morphology, greater rate of mitosis
Anaplasia
What grade is pilocytic astrocytoma (commonly-used name)?
Grade I
What grade is diffuse astrocytoma?
Grade II
What grade is anaplastic astrocytoma?
Grade III
What grade is glioblastoma multiforme (commonly-used name)?
Grade IV
Who do grade I astrocytomas tend to occur in?
children & young adults
Where are grade 1 astrocytomas often found in?
cerebellum, optic nerves, 3rd ventricle
What are characteristics of a grade I astrocytoma?
- Can be a solid or a cystic mass – either way, the tumour is well-differentiated and relatively easy to separate from surrounding normal brain tissue
- cells = large and have only have 2 processes
- few hemorrhage areas, less necrosis, preservation of BBB
What are the underlying processes that lead to grade I astrocytoma?
Usually excessive activation of Raf (gene called BRAF) –> Growth factors are responsible for activating
–> constantly having growth factor on
Who are grade II and III astrocytomas more likely to be found in?
adults
Where are grade II and III astrocytomas located?
tentorium of cerebellum
What are characteristics of Grade II astrocytoma?
poorly differentiated cells, invade surrounding brain
What are characteristics of grade III astrocytoma?
similar to grade II, but more mitotic figures, larger cells, more mitotic figures
What are mutations that cause grade II & III astrocytomas?
- PTEN: inactivated PTEN excessive signaling through the PI3K pathway
- Increased EGF or PDGF receptor activity or expression - Epidermal growth factor, platelet-derived growth factor
- P16, p14 or p53 inactivation
- IDH mutations – isocitrate dehydrogenase mutations that produce a metabolite (2-hydroxyglutarate) that “dysregulates” epigenetic signaling in the glial cell excessive activation of the RAS pathways