Nose, Epithelium - Degeneration
comment:Degeneration of the nasal epithelium ( Figure 1 , Figure 2 , Figure 3 , and Figure 4 ) is characterized by one or more of the following: loss of cilia, epithelial cell bleb formation, cellular disorientation, cellular eosinophilia, swelling, loss of cell-to-cell contact, or vacuolar changes within the epithelium. Degeneration may imply a current, ongoing process, so when the process seems to be active, the term "degeneration" may be appropriate. Degenerative changes may also occur in the epithelia of accessory nasal structures, possibly in the absence of degenerative changes in the lining epithelia. "Cystic degeneration" is reserved for epithelial-lined structures within the mucosa or lamina propria. Such cysts usually contain homogeneous or granular material. Epithelial degeneration is a common treatment-related lesion in toxicity studies but may also be seen in control animals.
recommendation:Epithelial degeneration should be diagnosed and assigned a severity grade whenever present. The type of epithelium should be included in the diagnosis as a site modifier (e.g., Nose, Olfactory epithelium - Degeneration). A thorough description of the lesion should be included in the report narrative, including identification of the target cell (e.g., sensory or sustentacular cells in the olfactory epithelium) if possible. Degenerative changes in the epithelium of an accessory nasal organ, in the absence of degeneration in other epithelial sites, should be diagnosed separately; if they occur as part of a more widespread degenerative epithelial process, then they should not be diagnosed separately but considered a component of that process and simply described in the pathology narrative. A diagnosis of cystic degeneration is appropriate when there are epithelial-lined structures in the nasal mucosa; this change should be given a severity grade and site identification. Associated lesions, such as inflammation, should be diagnosed separately if warranted by severity.
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