CNS Tumours Flashcards
How are CNS Tumours classified?
According to the presumed cell of origin.
Name the different types of cells of the CNS and the tumours they cause.
1.Glial cells-Astrocyomas,ependymoma,oligodendroglioma,glioblastoma
2.Primitive neuroectodermal cells-medulloblastoma,neuroblastoma
3.Nerve sheath cells-Schwannoma,Neurofibroma
4.Arachnoid cells-Meningioma
5.Lymporeticular cells-lymphoma
Examples of Extrinsic CNS Tumours
Meningiomas
neurofibromas
Schwannoma
Examples of Intrinsic CNS tumours.
1.Astrocytoma
2.Glioblastoma
3.Medulloblastoma
4.Oligondendrogliomas
5.Ependymomas
6.Choroid plexus papillomas
7.Hemangioblastoma
8.Lymphomas
9.Primitive neuroectodermal tumours.
Describe the ranking of CNS tumours in adults and children?
1.Adults-6th commonest
2.Children-2nd commonest
Why do CNS Tumours present with localising signs?
1.Tissue destruction
2.Non specific effects of raised intracranial pressure
Where are 70% of tumours in children situated?And what kind of tumours are most of them?
1.Posterior Cranial fossa
2.Intrinsic tumours
Where are 70% of tumours in adults situated?And what kind of tumours are most of them?
1.Supratentorially
2.Extrinsic and intrinsic both occur frequently.
What determines frequency of metastatic tumours?And what kind of tumours are most of them?
1.Age
2.Carcinomas
How do the metastatic tumours spread?
1.They form solid deposits in the CSF
2.Spread y speeding in the CSF
What does survival due to Metastatic tumours depend on?
Age,site,size and histology of the neoplasm
Pathogenesis of CNS tumour ?
Genetic
Chemical & viral
Radiation - ? Mobile phones
Immunosuppression – primary cns lymphomas
Trauma – role unproven
Describe the clinicopathological features of Brain tumours.
Brain tumors clinically present in two main ways;
Local effects – focal neurological signs eg epilepsy or paraplegia
Mass effects – non specific signs & symptoms of space occupying lesion ; herniation being the common cause of death
What perecentage of primary adult tumours do astrocytomas contribute to?
10%
Where do astrocytomas occur?
1.Children-cerebellum
2.Adults-Cerebral hemispheres
How are astrocytomas classified?
1.According to the predominant cell type and degree of differentiation
What does prognosis of Astrocytomas depend on?
1.Degree of differentiation
2.Age of pt
3.Site and size
What percentage of primary CNS tumours do glioblastomas contribute to?
30%
Where (in the brain) do glioblastomas occur?
In white matter of cerebral hemispheres.
How do glioblastomas arise/what are they due to?
De-differentiation from pre-existing astrocytomas
What does the prognosis of glioblastomas depend on?
Prognosis depends on similar features to astrocytomas
What is the commonest primitive neuroectodermal tumour?
Medulloblastoma
Where (in the brain) does a neuroectodermal tumour occur?
In cerebellum of children
Characteristics of Medulloblastomas?
Rapid growth with extensive infiltration,resluting in obstructive hydrocephalus.
CSF seeding is common.
Why has prognosis improved in medulloblastomas?
Because of radiotherapy
What is the chance of 5yr survival rate?
60%
What percentage of intracranial neoplasms in adults to meningiomas contribute to?
18%
Which group of people is at risk of meningiomas?
Female>males 2:1
From which cells do meningiomas arise from?
Arachnoid cells
Where do meningiomas usually occur in the rain?
parasagital region, sphenoid wing, olfactory groove & foramen magnum.
Describe the gross appearance of meningiomas?
1.Smooth lobulated broadly adherent to dura
2.May infiltrate dura & bone, exceptionally invade brain
3.May markedly compress the brain
How do metastatic tumours spread to the CNS tumours?
1.Hematogenous
2.Direct spread
What is the most common type of metastatic tumours and where are they from?
1.Carcinomas
2.kidney,colon,bronchus,breast and malignant melanimas
Where do metastatic tumours usually lodge?
At the boundary between grey and white matter
What happens if the metastatic tumours infiltrate into the subarachnoid space?
They cause carcinomatous meningitis
Examples of Intrinsic CNS tumours.
1.Astrocytoma
2.Glioblastoma
3.Medulloblastoma
4.Oligondendrogliomas
5.Ependymomas
6.Choroid plexus papillomas
7.Hemangioblastoma
8.Lymphomas
9.Primitive neuroectodermal tumours.
