View source for Central Nervous System Neoplasia

==Neoplasia==

* Particularly affects older animals.
* Signs may occur acutely, or be progressive and reflect
** The primary parenchymal damage by the tumour
** Sequelae such as haemorrhage or oedema.

==Primary==

===Meningioma===
[[Image:meningiomaleftfrontallobe.jpg|thumb|right|150px|Meningioma - left frontal lobe. Image couretsy of BioMed Archive]]
[[Image:meningiomabrain.jpg|thumb|right|150px|Meningioma. Image couretsy of BioMed Archive]]
* Meningioma is most frequently seen in cats and dogs, and is the most common primary brain tumour in these species.
** Dolicocephalic dog breeds are predisposed. [[Image:meningiomahisto.jpg|thumb|right|150px|Meningioma, histological view. Image couretsy of BioMed Archive]]
* Tumours arise from arachnoid cap cells ion the arachnoid layer of meninges.
* Meningiomas are usually benign, and therefore seldom invade. [[Image:meningiomainfiltrating.jpg|thumb|right|150px|Infiltrating meningioma, histological view. Image couretsy of BioMed Archive]]
** Spread to the lung has, however, been reported.
* The main effects of the tumour is due to its action as a compressive, space-occupying lesion.
* Meningiomas may become mineralised. <br><br>
<center>
{| border="1" cellpadding="7" 
!'''Feature'''
!'''Dog''' 
!'''Cat'''
|-
| '''Lesion Number'''
| Solitary
| Multiple
|-
| '''Infiltration to Cortical Parenchyma'''
| More infiltrative 
| Less infiltrative 
|-
| '''Encapsulation'''
| Poorly encapsulated
| Well encapsulated
|-
| '''Metastatic Potential'''
| Low
| Low
|}
</center>
[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_KSsrch&kw=MENINGIOMA View images courtesy of Cornell Veterinary Medicine]
====Treatment====

* Chemotherapy
* Radiation therapy
* Surigcal resection.
** Better results in cats (as encapsulated and clearly distinguished from normal brain).
*** Survival is 22-27 months following resection.

===Glioma===

* Due to their origin, gliomas are found within the intraaxial neuroxis.
* Brachycephalic breeds are predisposed.
* Glial tumours rise from cells of the brain parenchyma.
** Astrocytes - '''Astrocytoma'''
** Oligodendrocytes - '''Oligodendroglioma'''
** Ependymal cells - '''Ependymoma'''
** Choroid plexus cells - '''Choroid plexus tumours'''

====Astrocytoma====
[[Image:astrocytomagross.jpg|thumb|right|150px|Astrocytoma. Image courtesy of BioMed Archive]]
* The most common of the glial tumors
* Brachycephalic breeds are predisposed.
** E.g. boxer, bulldog.
[[Image:astrocytomahisto.jpg|thumb|right|150px|Astrocytoma: histological view. Image courtesy of BioMed Archive]]
=====Gross=====

* Astrocytomas are firm, solid tumours.
* Colour tends to be grey-white.
** This may sometimes be mottled with red due to areas of necrosis and haemorrhage.
[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_KSsrch&kw=ASTROCYTOMA View images courtesy of Cornell Veterinary Medicine]

====Oligodendroglioma====

* Oligodendroglioma is most commonly found in dogs.
* As for astrocytomas, there is a predilection for brachycephalic breeds.

=====Gross=====

* Oligodendrogliomas are soft in texture, and often gelatinous.
* Colour ranges from grey to pink/red.

[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_KSsrch&kw=OLIGODENDROGLIOMA View images courtesy of Cornell Veterinary Medicine]

====Ependymoma====

* Ependymomas are found in dogs, cats, [[Alimentary System  - Horse Anatomy|horses]] and cattle.
* They occur mainly in the ventricles.
** The lateral ventricle is most often affected.
* The tumours may spread within the ventricular system via the cerebrospinal fluid.
* Growth is generally expansile, but it can be invasive and destructive.

[http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_KSsrch&kw=EPENDYMOMA View images courstesy of Cornell Veterinary Medicine]

====Choroid Plexus Tumours====

* Choroid plexus tumours are rare.
* They are mainly found in dogs.
* Choroid plexus tumours are found in areas where the choroid plexus is concentrated, i.e.:
** Lateral ventricle
** Third ventricle
** Fourth ventricle
** There is a particular predilection for the fourth ventricle.
* This association with the ventricular system makes hydrocephalus a common sequelae.
* The tumours may metastasis via the CSF and ventricular system.
* Chroid plexus tumourc contain an increased concentration of blood vessels.
** Contrast administration may therefore aid in their identification.

====Treatment of Gliomas====

* The usual modes of anti-cancer therapy may be used to tackle gliomas:
** Radiation therapy
** Chemotherapy
** Surgery
* However, surgery is less ideal as the tumours are located within the parenchyma.

==PNETs==

* PNETs stands for Primitive NeuroEctodermal Tumors.
* These are tumors of primitive germ cell origin.
* They are rare.

==Secondary==

* May arise from:
** '''Metastasis'''
*** Numerous tumours of older animals may metastasise to the brain:
**** Haemangiosarcoma
**** Lymphoma
**** Mammary gland carcinomas
**** Other carcinomas
*** Tumours which metastasise to the lungs may be more likely to metastasise to the brain.
*** Incidence is underestimated, as the brain is not routinely examined at necropsy.
*** The white-grey matter junction is the most frequently affected area.
*** Brainstem and spinal cord metastasis are less common than forebrain metastasis.
*** Choroid plexus tumours and ependymomas may metastasise via the CSF.
** Extenstion from extraneural sites, e.g. 
*** Skull
*** Nasal cavity
**** Signs of extenstion may preced signs of nasal disease.
*** Frontal sinuses


[[Category:Central Nervous System - Pathology]]
[[Category:Neoplasia]]