Oral voriconazole therapy in cats with histoplasmosis yielded mild side effects and a favorable outcome.

OBJECTIVE: Infection by Histoplasma organisms most commonly results in disseminated systemic infection in cats. Relapse during therapy with itraconazole and fluconazole has been reported. The aim of this study was to report the clinical response, duration of therapy, side effects, and outcome in cats with histoplasmosis that were treated with voriconazole. ANIMALS: 6 client-owned cats. CLINICAL PRESENTATION: Medical records were reviewed of cats with confirmed histoplasmosis that presented to the Kansas State University Veterinary Health Center and received voriconazole therapy (n = 6 cats). RESULTS: 4 cats were switched to voriconazole from fluconazole (n = 2), itraconazole (1), or both (1), and 2 cats received voriconazole as initial therapy. Median starting dosage was 3.51 mg/kg PO every 72 hours. Two cats required a change in dosing interval from every 72 hours to every 96 hours due to hyporexia (n = 2) and an elevated ALT (1). Remission was documented in all 6 cats with a median time to a negative urine antigen of 256 days (range, 94 to 494 days). CLINICAL RELEVANCE: Voriconazole therapy in 6 cats with histoplasmosis yielded mild side effects and a favorable outcome. Reported dosages provide a feasible alternative to daily dosing for owners of feline patients.

Feline sarcomatoid renal cell carcinoma with peritoneal carcinomatosis and effusion.

A 9-y-old, castrated male, domestic medium-hair cat diagnosed previously with chronic kidney disease developed anorexia and vomiting. Ultrasonography revealed abdominal effusion and a left renal perihilar mass. Cytologic evaluation of the peritoneal fluid and mass identified atypical epithelioid cells suspected to be of renal epithelial or possible mesothelial origin. Immunohistochemical (IHC) evaluation of a formalin-fixed, paraffin-embedded peritoneal fluid cell block indicated both pancytokeratin and vimentin expression in the atypical epithelioid cell population. With scanning electron microscopic evaluation, similar epithelioid cells lacked the cell-surface microvilli expected of mesothelium, supporting an antemortem diagnosis of probable carcinoma. On postmortem examination, the left kidney was effaced by an infiltrative neoplasm with myriad similar nodules throughout the peritoneum. The neoplasm was composed primarily of polygonal-to-spindle-shaped cells with strong vimentin and weak pancytokeratin cytoplasmic immunolabeling. Further IHC characterization with PAX8, CK18, KIT, napsin A, SMA, desmin, CD18, and claudin 5 was performed. Histologic and IHC findings supported a diagnosis of sarcomatoid renal cell carcinoma with peritoneal carcinomatosis. An in vitro cell culture line of neoplastic cells harvested from the primary tumor was successfully established for future research endeavors.