Bath Vet ReferralsCase presentation
A 3 year old neutered female DSH cat presented with a 7 day history of cat flu like signs, including sneezing and a right sided purulent discharge. There was minimal response to antibiotic treatment. She then developed a swelling over the right frontal sinus, became ataxic and started to head press. Examination revealed her to be obtunded and ataxic with proprioceptive deficits in all four limbs.

Question: What is your neurolocalisation?
Question: What are your likely differentials?

For further investigations, discussion and the answer to these questions, please scroll down the page.



















Further investigations
A number of tests had been performed at the referring veterinary practice. Routine haematology and biochemistry at the referring vets were unremarkable. A nasal biopsy had shown a granulomatous inflammation, and a Pasteurella species was grown. FIV and FeLV testing was negative. Aspergillus serology was negative. Nasal radiography showed soft tissue density within the nasal cavity but no osteolysis. MRI of the brain was performed at Bath Veterinary Referrals.

Fig 1. T1 weighted parasagittal MRI of the brain and nasal cavity.

Fig 2. T1 weighted parasagittal MRI scan of the brain and nasal cavity post gadolinium contrast. Compared to figure 1, it can be seen there is contrast uptake in the nasal cavity and extending into the frontal lobes of the cerebrum.

Fig 3. T1 weighted dorsal view MRI of the brain and nasal cavity

Fig 4. T1 weighted dorsal MRI of brain and nasal cavity after gadolinium contrast. There is contrast enhancement of a mass extending from the nasal cavity through the cribriform plate into the frontal lobes.

The owner elected euthanasia while the cat was still under anaesthetic at this stage. A post mortem examination was carried out with the owner's permission (fig 5)

Fig 5. Post mortem examination of this case. Rostral is to the bottom of the picture. An irregular mass can be seen filling the nasal cavity and extending through the cribriform plate into the brain. Some purulent discharge from the fronal sinus is also visible on the right of the picture.

Histology demonstrated the mass to be nasal lymphoma, with extension into the ethmoidal cribriform plates, frontal meninges and into the frontal cerebral cortex.

Nasal lymphoma is one of the most common nasal tumours in cats, and the nasal cavity is the most commonly affected site for extranodal neoplasia in cats. One retrospective study of 97 cats with nasal lymphoma showed an overall median survival time of 172 days, with no difference being found between cats that were treated with radiotherapy alone, chemotherapy alone or radiotherapy + chemotherapy (Haney et al 2009).

Haney et al (2009), JVIM, 23, 287
Sykes et al (2010), JVIM, 24, 1427

Question. What is your neurolocalistion?
Answer. Proprioceptive deficits can arise from lesions in the forebrain, brain stem, spinal cord, and peripheral nerves. Assuming the obtundation was related to the ataxia, this implies forebrain involvement.

Question. What are your most likely differentials?
Answer. If the nasal signs were related to the neurological signs, then a process affecting both the nasal cavity and forebrain is suspected. Differentials include a neoplastic disease extending locally from nasal cavity to brain, or less likely a fungal disease. Cryptococcosis can affect the brain and the nasal cavity, and has been reported to cause gelatinous pseudocyst and granulomatous mass lesions in the CNS (Sykes et al 2010). However cryptococcosis is uncommon in the UK. Other differentials include viral infections such as FIP, FIV and FeLV.

First published Thu, Mar 24 2011