Primary liver neoplasms: evaluation of proliferative index using MoAb Ki67.

Thirty-two cases of primary liver neoplasms comprising 12 benign, 15 malignant, and 5 cases with equivocal histopathological features between benign and malignant have been investigated using monoclonal antibody (MoAb) Ki67, which reacts with a nuclear protein expressed in the G1, G2, S, and M phases of the cell cycle. The Ki67 score (positive cells/total neoplastic cells) seems to correlate to the classes of lesions tested. In the hepatocellular carcinoma (HCC) group, the percentage of labelled nuclei, ranging from 15 to 50 per cent, showed a good correlation with Edmondson-Steiner's histological tumour grade. A percentage of positive cells similar to that of the proved low-grade HCCs was detected in the five neoplastic lesions in which the routine histopathological criteria of malignancy were not fulfilled. The benign neoplasms showed a very low growth fraction, similar to that of normal or cirrhotic tissues. The use of the Ki67 score seems to offer useful information about the biological behaviour of some liver masses and may help in the differential diagnosis of hepatocellular adenoma versus carcinoma.