Liver - Hepatodiaphragmatic Nodule
comment:Protrusion of a portion of the median lobe into the diaphragm represents a congenital lesion in rats of any age and is occasionally seen in mice. This anomaly involves both the liver and the diaphragm. The protrusion of the liver does not penetrate the diaphragm but is covered by the thin fibrous tendon of the diaphragm. These nodules typically are not well demarcated and have normal hepatic architecture ( Figure 1 ). Hepatocyte nuclei within the nodule may contain linear chromatin arrangements resembling nuclear profiles seen in Anitschkow myocytes ( Figure 2 and Figure 3 ).
recommendation:Although this is a background lesion that occurs sporadically and is not affected by treatment, it is a congenital lesion and should be diagnosed whenever present. These lesions should not be graded.
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National Toxicology Program. 1982. NTP TR-228. Carcinogenesis Bioassay of Vinylidene Chloride (CAS No. 75-35-4) in F344/N Rats and B6C3F1/N Mice (Gavage Study). NTP, Research Triangle Park, NC. Full Text: http://ntp.niehs.nih.gov/ntp/htdocs/LT_rpts/tr228.pdf
Thoolen B, Maronpot RR, Harada T, Nyska A, Rousseaux C, Nolte T, Malarkey D, Kaufmann W, Kutter K, Deschl U, Nakae D, Gregson R, Winlove M, Brix A, Singl B, Belpoggi F, Ward JM. 2010. Hepatobiliary lesion nomenclature and diagnostic criteria for lesions in rats and mice (INHAND). Toxicol Pathol 38:5S-81S. Full Text: http://tpx.sagepub.com/content/38/7_suppl/5S.full
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