Hyperplastic lesions, especially areas and nodules of hyperplasia, developed in the liver of Donryu rats fed 0.03% 2-fluorenylacetamide (2-FAA) diet, were examined histochemically and histologically, and compared with hepatomas. Areas of hyperplasia showed a moderate to marked decrease in β-glucuronidase, glucose-6-phosphatase, canalicular ATPase, and phosphorylase activities, and slight to moderate decrease of acid and alkaline phosphatase activities, SDH activity, and glycogen level. Occasional increase was also observed in the activity of phosphorylase, canalicular activity of ATPase, and alkaline phosphatase. The enzymic deviation in the areas of hyperplasia lasted long, except that of more or less prominent increase in lysosomal or canalicular enzymes that occurred with time.
Nodules of hyperplasia showed principally similar histochemical features as areas. Only in the former, however, the decrease of glucose-6-phosphatase and canalicular ATPase and alkaline phosphatase, and glycogen levels were usually more marked. Occasionally increased β-glucuronidase activity was also observed in the nodules of hyperplasia.
When the histochemical features of areas and nodules of hyperplasia were compared with those of hepatomas, similarities were emphasized, although in some hepatomas abnormal staining patterns and variability of the levels of some enzymes within a lesion were observed. The histochemical findings indicate that the two kinds of hyperplastic lesions and hepatomas are to be classified in the same category so far as they are definitely and persistently deviated from normal liver cells.