Table 14-9.
Primary Tumors of the Nervous System
| Cell of Origin | Tumor Type | Location | Species Affected | Gross Appearance |
|---|---|---|---|---|
| CNS | ||||
| Embryonal cell | Medulloblastoma | Cerebellum (WM&GM) | Dog, cow, cat, pig (young animals) | Well-circumscribed, soft, gray to pink expansile mass (usually does not have hemorrhage, cysts, or necrosis). |
| Oligodendroglia | Oligodendroglioma | Cerebrum, brainstem, interventricular septum (WM&GM) | Dog, cat, cow | Well-demarcated, gray to pink-red, soft or gelatinous expansile mass, usually with areas of hemorrhage. |
| Astroglia | Astrocytoma | Pyriform lobe, cerebral hemispheres, thalamus-hypothalamus, midbrain, cerebellum, spinal cord (WM&GM) | Dog, cat, cow | Poorly demarcated, firm, gray-white when well differentiated; anaplastic neoplasms are moderately to well-demarcated, soft and friable (usually with areas of necrosis, hemorrhage, edema, and cavitation). |
| Ependyma | Ependymoma | Ventricular system (lateral; less commonly, third and fourth), central canal of the spinal cord | Dog, cat, cow, horse | Poorly to moderately to well-demarcated, soft and gray-white, invasive, destructive gelatinous expansile mass (usually with areas of hemorrhage and cavitation). |
| Choroid plexus epithelium | Choroid plexus tumor | Ventricular system (fourth; less commonly, third and lateral) | Dog, horse, cow | Well-demarcated, granular to papillary, gray-white to red, expansile mass. |
| Microglia | Microgliomatosis | Cerebrum, brainstem | Dog | Poorly demarcated, gray-white, infiltrative mass (may have perivascular pattern). |
| Endothelium | Hemangiosarcoma | Cerebrum, brainstem | Dog | Well-demarcated, invasive red to dark red, expansile mass. |
| Arachnoid cells | Meningioma | Meningeal surface of the CNS (convexity and lateral surfaces of the cerebral hemispheres, tentorium cerebelli, flax cerebri, ventral brainstem, spinal cord) | Cat, dog, horse, cow, sheep | Well-demarcated, variable shapes, firm, encapsulated, and gray-white to soft, red-brown or gray, expansile masses (usually with areas of hemorrhage and necrosis). |
| PNS | ||||
| Schwann cells (other supportive cells) | Peripheral nerve sheath tumor* | Cranial nerves, spinal nerves (brachial plexus) | Dog, cow, cat | Firm or soft (gelatinous), white or gray, nodular masses. |
CNS, Central nervous system; PNS, peripheral nervous system; WM&GM, white matter and gray matter.
*
Other names for this tumor type include schwannoma, neurofibroma, and neurilemmoma.