Neoplastic liver nodules of unknown cause in a colony of sand rats (Psammomys obesus)
Adler, J.H.; Roderig, H.; Ungar, H.
Israel Journal of Medical Sciences 12(10): 1212-1215
1976
ISSN/ISBN: 0021-2180 PMID: 990139 Document Number: 105506
The nodules were classified as benign tumors. In view of the absence of structural distortion, the isomorphic appearance of the hepatocytes composing the nodules, the signs of expansive growth and the absence of invasive growth, the term benign hepatoma appears adequate. The absence of bile duct proliferation amd cirrhotic changes further support the diagnosis of a primary neoplasm. Since nearly 1/2 of the animals older than 19 mo. had visible nodules, while none were seen in the younger age groups, an unknown tumorigenic factor (or combination of factors) must have acted for the greater part of the life span of the animals before the tumors became evident. Tumor formation may also be related to the aging process. Particular attention should be paid to the reported findings if P. obesus is to be used in long-term studies of the effects of toxic and, in particular, carcinogenic agents. Similar precautions should be observed with regard to certain mouse strains and other animals known to develop spontaneous liver tumors.