Invasive mould infections of the naso-orbital region of cats: a caseinvolving Aspergillus fumigatus and an aetiological review

This report describes a cat diagnosed with Aspergillus fumigatus sino/nasal/orbital infection using ocular ultrasound, CT scan, magnetic resonance imaging, histopathology, and culture. Etiology, clinical aspect and treatment are discussed with reference to a literature review of invasive mold (i.e filamentous fungi) infections involving tissues of the naso/orbital region of cats. These forms can present with different localizations (nasal passages, sinuses, orbits, subcutaneous spaces, palate etc.) depending on the fungal species and its way of introduction into the tissues. Cases with localized subcutaneous lesions (swellings, ulcerations, masses, nodules etc.) but without concomitant signs of nasal/orbital disease generally result from traumatic injuries resulting in the inoculation of fungal spores in the subcutaneous space. In contrast, in patients with lesions in the naso-ocular area and concurrent signs of nasal disease (nasal discharge, sneezing, masses protruding from the nostrils), primary infection likely results from the inhalation of spores, with the infection subsequently spreading to the nasal planum or penetrating overlying bones to invade the subcutaneous space. Aspergillus spp. typically shows such an invasion mechanism and frequently affects orbital tissues. Interestingly, Cryptococcus neoformans, yeast that represents the most frequent fungal species causing sino-nasal pathology in cats, has been shown to invade sino-nasal structures but not involve orbit. Dematiaceous fungi (i.e filamentous fungi with brown/black hyphae) are reported to cause solitary, less invasive, slowly developing lesions, probably as a result of traumatic injuries with inoculation of fungal propagules. Accordingly, the subcutaneous space is more frequently primarily involved. Whatever the mold involved, reported treatment options include surgery and a series of antifungal drugs. Outcome is frequently poor, especially for Aspergillus spp. infections, although various measures can be taken to maximise the chances of success, as discussed in the present report