Proliferative and Neoplastic Lesions in the Rodent Nasal Cavity

Abstract

Proliferative lesions in the rodent nasal cavity are reviewed; attempt was made to compare species affected, sex differences, strain differences, route of administration and tumor types occurring both spontaneously and after induction by different chemicals. This review is not meant to be all inclusive but to be representative of observed trends. Our general conclusions in this paper are that: 1) spontaneous nasal tumors in rodents are very rare; 2) spontaneous nasal tumors in rats are most often squamous cell tumors, whereas hemangiomas or respiratory adenomas predominate in mice and squamous cell tumors are rare; 3) rats are usually more susceptible to the induction of epithelial tumors of the nasal cavity than mice; 4) chemically-induced hemangiomas and hemangiosarcomas of the nasal cavity have only been reported in mice; 5) tumors of the olfactory epithelium are almost uniformly malignant and invasive, while nonsquamous tumors of the respiratory epithelium are typically less invasive; 6) chemically-induced tumors of the olfactory region, either mesenchymal or epithelial, do not always require an inhalation route of exposure but may occur by systemic targeting of this region; and 7) chemicals inducing tumors in the olfactory region often produce a variety of tumor morphologies in this location as well as squamous and polypoid tumors of the transitional region. More work will be needed to illucidate the mechanisms of nasal carcinogenesis and to further refine the current tumor classification system.

Morphology of Nasal Lesions in F344/N Rats Following Chronic Inhalation Exposure to Naphthalene Vapors

“…The results of this study are consistent with the general observation that rats are more susceptible to epithelial tumors of the nasal cavity than mice (3,4). In addition to differences in site-specific metabolism in rats and mice, the tendency for rats to develop nasal tumors, while mice develop lung tumors, following exposure to naphthalene may be partly related to anatomic differences in the nasal passages in these two species.…”

Evolution of Alachlor-Induced Nasal Neoplasms in the Long-Evans Rat

“…As shown in Figure 10, (1,4,12). Further, the fact that the glandular contents of the tumors were consistently PAS positive strengthened this diagnosis (4). These morphologic changes occurred specifically in the ventral and lateral regions of the posterior nasal cavity.…”

Respiratory Tract Lesions in Noninhalation Studies

“…Polypoid adenoma ( Figure 1E) was the most commonly induced adenoma in the nasal cavity (Brown et al, 1991), arising in the anterior nasal cavity from the respiratory epithelium of the nasoturbinates, maxilloturbinates, or lateral wall of the nasal cavity. Polypoid adenomas were sessile or pedunculated tumors formed of nonciliated cuboidal to low columnar cells that formed solid sheets or microcysts (Kerns, 1985).…”

“…Several types of olfactory neuroblastomas were described (Brown et al, 1991). One type was composed of cells with features of sustentacular cells in solid masses, with gland-like structures or rosettes being formed.…”