A 14-year old female Jack Russell Terrier was presented with two-week history of aggressive behavioural change. Neurological examination was unremarkable. Haematology and biochemistry were largely normal. CT scan of the brain revealed a mass with a hypodense centre and mild contrast ring enhancement in the left caudal olfactory lobe, compressing the rostral left ventricle. CSF analysis revealed xanthochromia, increased protein and marked pleocytosis with predominance of neutrophils and RBC. The differential diagnosis included abscessation, inflammatory diseases, neoplasia and haemorrhage. MRI was performed two weeks later, which revealed a mass apparently within the left lateral ventricle. It was hyperintense to isointense on T1-weighted images and hypointense to isointense on T2-weighted images. A signal void representing magnetic susceptibility artefact was seen on gradient echo sequences. The differential diagnosis at this stage included haematoma or haemorrhage associated with neoplasia. The dog was euthanised and post-mortem examination was carried out. This revealed an organised sub-ependymal periventricular haematoma arising from the region of the left caudate nucleus and protruding into the left lateral ventricle.
An underlying vascular malformation is suspected based on the imaging and pathological findings. This is a rare condition and may mimic neoplastic disease.