Chronic rhinosinusitis and rhamphothecal destruction in a major mitchell's cockatoo (Cacatua leadbeateri) due to Cryptococcus neoformans var gattii

A 7-year-old male Major Mitchell's cockatoo (Cacatua leadbeateri) was presented with an encrusted beak tumor. Clinical examination demonstrated a bird that was bright and alert and had good pectoral muscle condition. The bird was open-mouth breathing and had a bilateral mucopurulent ocular discharge. A relatively well-demarcated thick crust overlaid the right naris and extended along the right lateral wall of the rhamphotheca. Radiographs of the head demonstrated a diffuse increased radiodensity of the nasal sinuses. A diagnosis of cryptococcosis was made by examining Wright's-stained choanal smears, which demonstrated a mixed overgrowth of gram-negative coccobacilli and occasional aggregates of encapsulated yeast organisms measuring 6-10 μm within 8- to 12-μm nonstaining capsules. The bird was euthanized, and necropsy findings were confined to the nasal and infraorbital sinuses. The sinuses contained a pale, gelatinous substance, which yielded a heavy growth of Cryptococcus neoformans var gattii on culture. Histopathologic examination confirmed a diagnosis of nasal cryptococcosis with severe infiltration of the nasal passages with cryptococci and subsequent destruction of the rhamphotheca.