Salivary Gland - Karyomegaly

Image of karyomegaly in the salivary gland from a male B6C3F1 mouse in a chronic study
Salivary gland - Karyomegaly in a male B6C3F1 mouse from a chronic study. The nuclei in the acinar cells are enlarged.
Figure 1 of 2
Image of karyomegaly in the salivary gland from a male B6C3F1 mouse in a chronic study
Salivary gland - Karyomegaly in a male B6C3F1 mouse from a chronic study (higher magnification of Figure 1). The nuclei in the acinar cells are enlarged.
Figure 2 of 2
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comment:

Karyomegaly (enlarged nuclei) is an uncommon finding in NTP studies. The enlarged nuclei may make the entire cell appear to be enlarged. In NTP studies, karyomegaly in the salivary glands has been seen in control and treated F344/N and Osborne Mendel rats and a single B6C3F1 mouse ( Figure 1image opens in a pop-up window and Figure 2image opens in a pop-up window ). Enlarged nuclei can also be seen in basophilic hypertrophic foci, although they may be obscured by the basophilic cytoplasm.

recommendation:

Whenever present, this change should be diagnosed and graded based on the size of the nuclei and the number of nuclei affected. Karyomegaly within basophilic hypertrophic foci or within proliferative lesions should not be diagnosed separately. If the entire cell is enlarged (including the nucleus), the pathologist will have to use his or her judgment as to whether kayromegaly or hypertrophy (or both) would be most appropriate diagnosis.

references:

Jackson CD, Blackwell BN. 1991. Subchronic studies of tripelennamine in B6C3F1 mice. Int J Toxicol 10:503-510.
Abstract: http://ijt.sagepub.com/content/10/5/503.abstract

Neuenschwander SB, Elwell MR. 1990. Salivary glands. In: Pathology of the Fischer Rat (Boorman GA, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 31-42.
Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563