Choroid plexus tumor
Due to their cell of origin, they tend to arise within the ventricular system and can block drainage of CSF, thus a small tumor can cause very severe neurologic signs.
These tumors are reddish, papillary growths that may bleed.
Histologically, they are well defined, grow by expansion, and have a granular papillary appearance.
In both benign and malignant variants of choroid plexus papillomas, dissemination to other areas of the brain or spinal cord via the CSF pathways may occur following exfoliation. Obstructive hydrocephalus may occur. Meningeal carcinomatosis may follow spread of the tumor in the subarachnoid space.
Choroid plexus tumors are seen as well-defined, hyperdense masses with marked, uniform contrast enhancement on CT scans.
Marked enhancement, potentially including hemorrhage and mineralization, is also seen with MRI.
Choroid plexus papillomas have no apparent predilection for brachycephalic dogs.