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. 2020 Jan;32(1):162-165.
doi: 10.1177/1040638719897610. Epub 2019 Dec 26.

Rhinosinusitis in an Australian Mare Caused by Flavodon flavus, a Recently Recognized Invasive Fungal Pathogen of the Horse

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Free PMC article

Rhinosinusitis in an Australian Mare Caused by Flavodon flavus, a Recently Recognized Invasive Fungal Pathogen of the Horse

Willy W Suen et al. J Vet Diagn Invest. .
Free PMC article

Abstract

We describe herein the clinical, endoscopic, computed tomography (CT), pathologic, and microbiologic features of an infection caused by an under-recognized fungal pathogen, Flavodon flavus, in a 25-y-old Australian Quarter Horse. The horse had a unilateral obstructive nasal mass, resulting in stertor and dyspnea. On endoscopy, the mass was tan, multinodular, and completely obstructed the nasal passage. CT analysis revealed a large, soft tissue-attenuating and partially mineralized mass in the right nasal passage and dorsal-conchofrontal sinus, expanding into adjacent paranasal sinuses with associated bone lysis and rhinosinusitis. Histopathology of the mass on 2 occasions revealed suppurative inflammation initially, and pyogranulomatous inflammation subsequently. The inflammatory reaction surrounded numerous spherical fungal structures (~60-80 µm diameter) that stained positively on periodic acid-Schiff and Grocott methenamine silver stains. PCR for the fungal internal transcribed spacer 1 and 2 regions followed by Sanger sequencing on a cultured isolate identified the agent as F. flavus, which has only been reported previously as pathogenic in one horse in the United States, to our knowledge. Previous reports described this fungus as a nonpathogenic, environmental commensal fungus associated with insects and plants.

Keywords: equine; fungal granuloma; fungal rhinitis; nasal granuloma; sinusitis.

Conflict of interest statement

Declaration of conflicting interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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