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The present research was designed to assess the potential for progressive growth of hyperplastic, adenomatous, and carcinomatous mouse liver lesions grafted into syngeneic hosts and to determine the effect of treatment type, donor age, and metastatic potential on this parameter. Lesions were obtained from male B6/C3F1 mice fed on an open formula (NIH-007) diet or the same diet mixed with a chlorinated hydrocarbon pesticide (3,5-dichloro-(N-1,1-dimethyl-2-propyl)benzamide) (DcB). Animals were killed at 18 or 24 months of age. Hosts for transplanting were killed at 8 months, or when grafts reached 2 cm in diameter. Lesions diagnosed as nonmalignant (hyperplastic or benign) were more likely to grow after transplantation if obtained after 24 months, rather than after 18 months (0.025 less than p less than 0.05). There was a close correlation between donor lesion morphology and ability to grow in a recipient mouse (p less than 0.0005; 36% of the hyperplastic, 32% of the adenomatous and 79%, of the malignant lesions grew). The majority of lesions retained the morphologic appearance of the donor lesions. Transplanted lesions from control mice were more likely to grow than were those from DCB-treated mice (0.01 less than p less than 0.025). This correlation was particularly strong for hyperplastic nodules. Metastatic capability in the donor animals correlated positively with both growth potential (p less than 0.01) and growth rate (p less than 0.05) in recipient mice. These findings suggest that progression toward autonomous growth may occur both within the original host and during a prolonged transplantation period, making data interpretation difficult. Lesion morphology alone may not be adequate for assessing capacity for autonomous growth. Other factors, such as evidence of metastasis or local invasion in the primary host, may be required to make more meaningful diagnosis.

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