Difference between revisions of "Glioma"

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Glioma (view source)

Revision as of 08:23, 4 April 2022

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Major update in CNS tumour taxonomy
(Major update in CNS tumour taxonomy)
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==Classification==
==Classification==


Gliomas are classified by cell type, by WHO grade, and by location.
Gliomas are classified by cell type, by CNS WHO grade, patient age and by location.


===By type of cell===
===By type of cell===
Gliomas are named according to the specific type of cell with which they share histological features, but not necessarily from which they originate. The main types of gliomas are:
Gliomas are named according to the specific type of cell with which they share histological features, but not necessarily from which they originate. The main types of gliomas are:


* [[Astrocytoma]]s—[[astrocyte]]s ([[glioblastoma multiforme]] is a malignant astrocytoma and the most common primary brain tumor among adults).
* [[Glioblastoma]] is a malignant astrocytoma and the most common primary brain tumor among adults.
* [[Oligodendroglioma]]s—[[oligodendrocyte]]s
* [[Astrocytoma]]s—[[astrocyte]]s.
* [[Ependymoma]]s—ependymal cells
* [[Oligodendroglioma]]s—[[oligodendrocyte]]s.
* Mixed gliomas, such as [[oligoastrocytoma]]s, contain cells with different morphologies
* [[Ependymoma]]s—ependymal cells.
**Molecular analysis allows the tumor in most cases assigned to astrocytoma or oligodendroglioma.
* Glioneuronal and neuronal tumors.


Note:
Note:
Some authors consider [[choroid plexus]] as a specific type of glia, but [[choroid plexus tumors]] are usually not covered under the umberella term '''glioma'''.
Some authors consider [[choroid plexus]] as a specific type of glia, but [[choroid plexus tumors]] are usually not covered under the umberella term '''glioma'''.


===By WHO grade===
===By CNS WHO grade===
Gliomas are further categorized according to their grade, which is determined by [[pathology|pathologic]] evaluation of the tumor.
Gliomas are further categorized according to their grade, which is determined by [[pathology|pathologic]] evaluation of the tumor. Of numerous grading systems in use, the most common is the [[World Health Organization]] (WHO) grading system under which tumors are graded from 1 (least advanced disease—best prognosis) to 4 (most advanced disease—worst prognosis). Historically roman numerals were used for grading, but have been replaced by arabic numerals for grading within tumor types. Specific molecular features may influence tumor grading which is now a combination of histology and molecular neuroathology. Grading is based on expected biological behaviour, although proper treatment may heavily change prognosis.


*Low-grade gliomas [WHO grade II] are well-differentiated (not anaplastic);  these tend to exhibit  [[cancer|benign]] tendencies and portend a better prognosis for the patient. However, they have a uniform rate of recurrence and increase in grade over time so should be classified as malignant.  
*Low-grade gliomas [CNS WHO grade 1-2] are well-differentiated (not anaplastic);  these tend to exhibit  [[cancer|benign]] tendencies and portend a better prognosis for the patient. However, they have a uniform rate of recurrence and some diffuse gliomas may increase in grade over time and therefore calling these tumours benign is avoided.  
*High-grade [WHO grade III–IV] gliomas are undifferentiated or anaplastic;  these are [[cancer|malignant]] and carry a worse prognosis.
*High-grade [CNS WHO grade 3-4] gliomas are undifferentiated or anaplastic;  these are [[cancer|malignant]] and carry a worse prognosis.


Of numerous grading systems in use, the most common is the [[World Health Organization]] (WHO) grading system for astrocytoma, under which tumors are graded from I (least advanced disease—best prognosis) to IV (most advanced disease—worst prognosis).
 
===By patient age group===
The fifth CNS WHO edition recognizes following categories:
* Adult-type diffuse gliomas.
* Pediatric-type diffuse low-grade gliomas.
* Pediatric-type diffuse high-grade gliomas.
* Circumscribed astrocytic gliomas.


===By location===
===By location===
Gliomas can be classified according to whether they are above or below a membrane in the brain called the tentorium. The tentorium separates the cerebru] (above) from the cerebellum (below).
* A supratentorial tumour is above the tentorium, in the cerebrum, and mostly found in adults (70%).
* An infratentorial tumour is below the tentorium, in the cerebellum, and mostly found in children (70%).
* The pontine is located in the pons of the brainstem. The brainstem has three parts (pons, midbrain, and medulla); the pons controls critical functions such as breathing, making surgery on these extremely dangerous.
 
* Anatomic separation is essential in ependymal tumors. They are classfied into three groups:
** Supratentorial ependymoma.
** Posterior fossa ependymoma.
** Spinal ependymoma.
 
 
* Some gliomas have a specific anatomic designation in their name, reflecting their predominant tumor location.
 
 


*The supratentorial is above the tentorium, in the cerebrum, and mostly found in adults (70%).
*The infratentorial is below the tentorium, in the cerebellum, and mostly found in children (70%).
*The pontine is located in the pons of the brainstem. The brainstem has three parts (pons, midbrain, and medulla); the pons controls critical functions such as breathing, making surgery on these extremely dangerous.


==Table of common gliomas==
==Table of common gliomas==
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