Nose - Fungus
comment:Fungal organisms are occasionally seen in the nasal cavities of mice and rats from NTP toxicity/carcinogenicity studies, more commonly in rats. Mats of fungal mycelia may occur within the nasal passages ( Figure 1 , Figure 2 , Figure 3 , and Figure 4 ), but tissue invasion is extremely rare.
Based on fungal morphology (characteristic fruiting heads and hyphal branching patterns) and reports in the literature, the fungal organisms are usually an Aspergillus sp., with Aspergillus fumigatus being the most common. Aspergillus spp. have characteristic fruiting heads and hyphal branching patterns ( Figure 3 ). The fungi are typically accompanied by suppurative inflammation. Changes such as hyperplasia and metaplasia are usually present in the adjacent epithelium, and there is often acute to chronic-active inflammation in the associated underlying lamina propria.
recommendation:Fungus should be diagnosed whenever present but should not be graded. The morphologic features of the fungal organisms should be described in the narrative. The fungal genera/species cannot be definitively identified by histopathology alone; however, it may be stated that the morphologic features are consistent with a particular type of fungal organism. When warranted by severity, all associated lesions should be diagnosed separately and assigned severity grades. Whenever possible, it should be noted in the narrative whether or not the associated lesions are secondary to the presence of the fungus or if they may be related to treatment.
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Everitt JI, Richter CB. 1990. Infectious diseases of the upper respiratory tract: Implications for toxicology studies. Environ Health Perspect 85:239-247. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1568352/
Herbert RA, Leninger JR. 1999. Nose, larynx, and trachea. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, ed). Cache River Press, Vienna, IL, 259-292.
National Toxicology Program. 1986. NTP TR-300. Toxicology and Carcinogenesis Studies of 3-Chloro-2-methylpropene (Technical Grade Containing 5% Dimethylvinyl Chloride) (CAS No. 563-47-3) in F344/N Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/6603
Nyska A, Kuttin ES. 1988. Upper respiratory tract infection in mouse and rats. Mycopathologia 101:95-98. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/2963960
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