Hepatobiliary System

Liver - Hepatodiaphragmatic Nodule

Narrative

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).

Recommendations:

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.

References:

Eustis SL, Boorman GA, Harada T, Popp JA. 1990. Liver. In: Pathology of the Fischer Rat (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 71-94.

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: https://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

All Images

Hepatodiaphragmatic nodule in a female F344/N rat from a subchronic study.

Hepatodiaphragmatic nodule in a female F344/N rat from a subchronic study. Note the linear chromatin arrangement in the nuclei.

Hepatodiaphragmatic nodule in a female F344/N rat from a subchronic study. Note the linear chromatin arrangement in the nuclei (higher magnification of Figure 2).

Authors and Reviewers

Author

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Reviewers

John Cullen, VMD, PhD, DACVP, FIATP
Anatomic Pathology, Professor
North Carolina State University College of Veterinary Medicine
Raleigh, NC

David E. Malarkey DVM, PhD, DACVP, FIATP
Head, National Toxicology Program Pathology Group
Cellular and Molecular Pathology Branch
Division of the National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC