Long-term follow-up of laryngeal Rhinosporidium seeberi diagnosed by PCR and treated with laser ablation and voriconazole nebulization in a retired thoroughbred polo horse.

A 21-year-old retired polo Argentinian thoroughbred horse from a teaching herd was presented for a routine bronchoalveolar lavage demonstration, during which an incidental finding of a granulomatous mass on the dorsal aspect of the epiglottis was made. Rhinosporidium seeberi was suspected from a histological section obtained from an initial biopsy, and the mass was removed via laser surgery for cytology and PCR. Sequencing of the PCR amplicons confirmed the diagnosis of R. seeberi. A treatment protocol of nebulized voriconazole for 10 d postoperatively was used. Long-term follow-up required 2 more laser surgeries plus oral fluconazole to resolve the remaining fungal spores. However, 2.5 y later, there was no evidence of remaining fungal spores. Key clinical message: Horses from endemic regions can potentially be exposed to R. seeberi. Based on its travel history, this horse may have contracted the infection in South America, California, or Alberta. Treatments administered, including diode laser resection, voriconazole antifungal nebulization, and oral fluconazole administration, were successful but required repeated interventions.