Ear, Canal - Dilation
comment:Dilation of the external ear canal ( Figure 1 , Figure 2 , and Figure 3 ) is usually secondary occlusion of the ear canal by plugs of sloughed keratin lamellae, cerumen, and necrotic debris that distends the canal. The lining epithelium may be hyperplastic. These findings usually occur in aged animals.
recommendation:Dilation of the ear canal should be diagnosed with an appropriate topography modifier (external ear canal, etc.). Dilation should be diagnosed as present (without assignment of a severity grade). Associated lesions such as inflammation or epithelial hyperplasia should not be diagnosed separately unless warranted by severity, though they can be described in the pathology narrative.
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National Toxicology Program. 1996. NTP TR-455. Toxicology and Carcinogenesis Studies of Codeine (CAS No. 76-57-3) in F344 Rats and B6C3F1 Mice (Feed Studies). NTP, Research Triangle Park, NC. Abstract: http://ntp.niehs.nih.gov/go/6054
Yoshitomi K, Brown. 1990. HR. Ear and pinna. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 227-238. Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563
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