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| + | ==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, [[Hindgut Fermenters - Horse - Anatomy & Physiology|horses]] and cattle. |
| + | * They occur mainly in the ventricles. |
| + | ** The lateral ventricle is most often affected. |
| + | * The tumours may spread withing 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 |