Cryptococcosis in a Cat

Background: Cryptococcosis is a mycosis that primarily affects domestic cats and is caused by fungi of the genus Cryptococcus, resulting in cutaneous, ocular, respiratory, and neurological manifestations. Diagnosis is based on the microscopic evaluation of the lesions and isolation of the causative agent. The aim of this study was to describe a case of feline cryptococcosis diagnosed by cytology and treated at the Veterinary Hospital of the State University of Santa Cruz (HV-UESC). Case:A 5-year-old uncastrated male cat was taken to the HV-UESC small animal clinic, owing to a gradual increase in the volume of the nasal plane spanning over a year, accompanied by respiratory distress. Upon physical examination, the animal was found to have regular nutritional status, dehydration, hypocorous mucosae, and enlarged popliteal lymph nodes. In addition, multifocal areas of ulceration on the body as well as increased volume in the nasal plane (clown nose) were observed. Peripheral blood samples were collected for complete blood count and biochemical analysis. Due to clinical suspicion of fungal lesions, fine needle aspiration of the nasal lesion was performed and cytological slides were sent to the HV-UESC histopathology laboratory. Probable diagnoses included rhinosporidiosis, cryptococcosis, and histoplasmosis. The animal was subjected to thoracic radiography in the imaging division of the HV-UESC. Blood counts revealed thrombocytopenia (130,000/mm3) and biochemical tests presented hypoproteinemia (3.2 g/dL), with hypoalbuminemia (1.52 g/dL); however, chest radiography did not show pulmonary alterations. Results of cytological analysis indicated pyogranulomatous inflammation associated with intracellular organisms, demonstrating a pathogen morphology similar to that of Cryptococcus spp. Before the diagnosis, itraconazole 5 mg/kg (1 capsule, twice a day for 30 days) and fipronil (1 ampoule 0.5 mL, on the back) were prescribed. Follow-up after 40 days showed a slight improvement in cutaneous lesions and respiration, and no other abnormalities were observed. At the follow-up, the owner disclosed that medication could not be administered at the prescribed frequency because of the animal often ran away from home and stayed without prescription. Due to unsatisfactory response to the first treatment, the dosage of itraconazole1 was increased to 10 mg/kg (1 capsule, twice a day, for 30 days) with a new regimen and follow-up after 15 days. However, the owner did not make a follow-up visit. A year later, after several attempts to contact the owner, we were notified that the treatment had been discontinued and the cat still presents with lesions. Discussion: Although cryptococcosis is not endemic, the cat roamed freely on the streets and may have been infected by inhaling the microorganism spores present in the environment. The clinical signs exhibited by the animal were consistent with the findings associated with Cryptococcus spp. infection in cats, especially the "clown nose" lesion. The cat, besides being dehydrated at the time of care, had a regular nutritional status. Cytology, the only diagnostic technique used in this case through which it was possible to visually identify the fungus, was definitive for the diagnosis of cryptococcosis. Although the prescribed treatment is one of the most indicated in such cases, it was not effective, possibly due to inadequate administration. The length of infection, discontinuation of therapy, and absence of follow-ups for clinical reassessment certainly contributed to an unfavorable prognosis.