Case Study – Nasal planum swelling in a 5 year old cat

Presenting Complaint:

A 5-year-old female, domestic shorthair cat presented with a three-week history of swelling of the nasal planum and nasal snuffling.  She had otherwise been well in herself and she had not shown a response to courses of potentiated amoxycillin or prednisolone.  She had limited access to the outdoors and was no known to fight.  She had no history of overseas travel and no significant prior medical history.

Diagnostic Testing:

Physical examination – normal apart from fleshy swelling of the nasal planum.  Ophthalmic examination and neurologic assessment were normal.

General bloods – normal

CT head – swelling of the nasal planum without deeper involvement in the nasal cavity or cranium.

Cytology – pyogranulomatous inflammation with intracellular yeast-like structures (orange arrow).

Cryptococcus antigen – positive at 256 (RI<8).

Diagnosis and Management:

Cryptococcus is a yeast infection that can cause nasal, ophthalmic and neurological signs and cats are particularly sensitive to the infection.  It is commonly seen overseas, especially in warmer climates, but is a rare cause of disease in the UK.  Fortunately, diagnosis is relatively straightforward with organisms often visible on cytology or histology and Cryptococcus antigen test proving a sensitive and specific test which is run on blood (serum). PCR and culture are also specific diagnostic tests.

While Cryptococcus is a life-threatening disease, patients that survive long enough to show a response to medication carry a fair prognosis.  In this case there were no neurological signs and the cat was otherwise well which were in her favour.  Amphotericin B is likely the most efficacious treatment but the challenges of administering this safely mean it is generally reserved for cases with life-threatening neurological signs.  Alternatively itraconazole and fluconazole are both effective with fluconazole showing improved outcome in some studies (as well as better CNS penetration and reduced side effect profile) and consideration should be given to using fluconazole (under the cascade).

Monitoring for drug side effects (hepatic parameters) and response with Cryptococcus antigen is recommended with treatment continuing for several months – until the Cryptococcus antigen returns to normal or 2-3 months beyond resolution of clinical signs.