Histopathological and immunohistochemical analysis of adenomatous hyperplasia and hepatocellular carcinoma: cellularity, thickness of cell cord, and Ki-67 proliferative activity.

To characterize adenomatous hyperplasia (AH) and hepatocellular carcinoma (HCC), and to establish their histopathological differences, morphometrical and immunohistochemical analyses, namely, cellularity, thickness of cell cord, and Ki-67 labeling index (Ki-67 LI) were done on surgically obtained hepatic lesions from patients with positive serum antibody against HCV. The hepatic lesions analyzed include chronic active hepatitis (CAH) (11 specimens), regenerative nodules of liver cirrhosis (LC) (29), AH (11), small HCC Edmondson's Grade I (GI) (19), GII (26), GIII (14). The results showed that AH has relatively high cellularity, and significantly greater thickness of cell cord than LC; whereas, HCC GI has significantly higher cellularity and Ki-67 LI than AH. From the data of these markers, and from the absence of conspicuous structural atypism, AH is considered to be in a different category from HCC GI. The premalignant potential of AH is supported only by its high incidence of coexistence adjacent to HCC GI or GII(6/11). Most lesions of HCC seem to develop from the liver tissue having a background of CAH or LC without passing through AH. Focal fatty changes are frequently observed within lesions of both AH and HCC GI (5/11, 8/19). When non-fatty regions of AH and HCC GI are compared, with respect to their markers, particularly Ki-67 LI, as well as the structural atypism, such as microacinus formation and pseudoglandular structure, and invasive growth into the surrounding liver parenchyma, HCC GI can be diagnosed as an early or well-differentiated malignant lesion.