Figure 4

FAS immunohistochemistry. Already at very low magnification, FAH can be identified in the liver tissue of diabetic rats after islet transplantation, owing to their strong FAS overexpression (a). At higher magnification (b), the typical morphology of these FAH becomes clear. An islet graft (I) is situated in a terminal portal venule, branching off an portal tract (middle left). The hepatocytes of such an FAH are enlarged, owing to an increase in glycogen and fat storage (fat vacuoles are in particular displayed in the upper right part of the FAH). At this early stage, these FAH are confined to the anatomical borders of the liver acinus, draining the blood from the islet graft and are demarcated by hepatic veins (upper right). These early clear-cell FAH, few weeks after islet transplantation, show very strong FAS overexpression. In cases, when the lesion has lost its clear-cell (glycogenotic) phenotype, FAS expression diminished, as it is shown in the basophilic hepatocellular adenoma (upper three quarter) depicted in (c). However, if the glycogenotic phenotype prevailed, the preneoplastic lesion or neoplasm also maintained its FAS overexpression. Panel d shows such a well-differentiated, glycogenotic and fat-storing hepatocellular carcinoma with retained FAS overexpression. Original magnification: × 25 (a), × 51 (b), × 254 (c) and (d).