S. Ambrosi, M.D., P. Di Zitti, M, M., A. Baiocchini, M. D.
The liver architecture was slightly disrupted with moderate lobular disarray, focal lobular necrosis and rare bridging fibrosis. The main histological feature was represented by the presence of a peculiar giant cell transformation of the hepatocytes which extensively and haphazardly occurred throughout liver parenchyma but was especially noticeable around centrilobular areas. Generally the giant cells had a tendency to occur in clusters. They contained multiple nuclei (ranging between 5 to 30) which frequently displayed well evident eosinophilic nucleoli. Their cytoplasm was pink and granular. No mitoses were seen. No viral inclusions were identified. In the remaining parenchyma, portal tracts contained an inflammatory infiltrate mainly consisting of mature lymphocytes, with occasional plasma cells. The mononuclear infiltrate invaded also the limiting plate surronding portal tracts; piece-meal necrosis was sometimes present but wasnt a striking finding. A lobular inflammation with a mononuclear infiltrate was also randomly found and occasionally occurred around Mallory bodies. Bile ductules showed only focal and mild proliferation in a few intralobular secta. Bridging fibrosis was very scanty and mild. No cholestatic plugs were found.
CD 68 granular immunostaining was observed throughout the parenchyma in the cytoplasm of Kupffer cells and giant hepatocytes. Moreover, these latter showed a strong cytoplasmic immunoreaction for CK 8,18 (CAM 5.2) and a negative reaction for CK 7 and CK19. These latter cytokeratin filaments were well evident in biliary ductules.
Light microscopy of the second biopsy performed six months later revealed a less prominent portal tract inflammatory infiltrate, with only a few lymphocytes in lobular parenchyma. The number of giant hepatocytes was otherwise similar to that seen in the first biopsy sample; they were located in perivenular areas, sometimes within small areas of confluent necrosis.