Disseminated histoplasmosis in a Brazilian domestic cat: early diagnosis and successful treatment

Histoplasmosis is a worldwide distributed opportunistic mycosis caused by the dimorphic fungus Histoplasma capsulatum. It is reported in cats with non-specific clinical signs. The aim of this case report is to describe the first case of disseminated histoplasmosis in a cat in the city of Santa Maria, Rio Grande do Sul, Brazil. In veterinary consultation, it was reported that the animal had a history of vomiting, hematochezia, and weight loss for 3 months. At physical exam, an abdominal lymph adenomegaly, an intestine diffusely enlarged, and a poor body condition were observed. Ultrasound-guided fine-needle aspiration cytology (FNAC) of the caudal mesenteric lymph node was performed. Cytology revealed pyogranulomatous infiltrate with the presence of yeast organisms, cells compatible with H. capsulatum. The treatment prescribed was itraconazole. Culture of the caudal mesenteric lymph node sample confirmed the cytological diagnosis. Physical, hematological, and ultrasonographic exams were undertaken periodically. On day 139 of treatment, the itraconazole dose was increased once the patient had anemia and periodic vomiting; also, the abdominal lymph node size decrease was not remarkable. After that, the cat showed a better clinical response. On day 459 of treatment, the owners had decided to interrupt the treatment but the cat was still referred to the hospital for clinical and ultrasound evaluation. Fifteen months post diagnosis, the patient was alive and healthy. Feline histoplasmosis is an uncommon disease in our region. Therefore, this manuscript alerts veterinarians to the presence of this infection in the region of Santa Maria and emphasizes the importance of FNAC as a diagnostic tool for infectious diseases.