Liver, Bile Duct - Hyperplasia
comment:
Bile duct hyperplasia is not commonly seen in prechronic studies but is a common aging lesion. In chronic studies, the occasional occurrence of bile duct hyperplasia in the absence of any differences in incidence or severity among study groups likely represents a background lesion. It is more commonly seen in rats than in mice. Only some portal areas may be affected. Biliary hyperplasia may be associated with peribiliary fibrosis. When accompanied by inflammatory cells and/or oval cell proliferation, bile duct hyperplasia may be the consequence of a toxic insult. Figure 1

recommendation:
Bile duct hyperplasia should be diagnosed and assigned a severity grade whenever present as a treatment-associated change or when excessive, as in this example. Since bile duct hyperplasia is a common age-related change, the decision to diagnose it will depend upon the age of the animal. Associated lesions, such as inflammation, fibrosis, or bile duct dilation, should be diagnosed separately if warranted by the severity of these lesionsreferences:
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Greaves P. 2007. Histopathology of Preclinical Toxicity Studies: Interpretation and Relevance in Drug Safety Evaluation, 3rd ed. Elsevier, Amsterdam. Abstract: http://www.sciencedirect.com/science/book/9780444527714
Harada T, Enomoto A, Boorman GA, Maronpot RR. 1999. Liver and gallbladder. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 119-183. Abstract: http://www.cacheriverpress.com/books/pathmouse.htm
Hardisty JF, Brix AE. 2005. Comparative hepatic toxicity: Prechronic/chronic liver toxicity in rodents. Toxicol Pathol 33:35-40. Full Text: http://tpx.sagepub.com/content/33/1/35.full.pdf
Haschek WM, Rousseaux CG, Wallig MA. 2010. Fundamentals of Toxicologic Pathology, 2nd ed. Academic Press, San Diego, 197-235.
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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