Histological and immunohistochemical pattern of hepatocellular cytokeratin 7-positive and negative : Comparison by computerized morphometry

Objective: To investigate by computerized morphometric the morphological features in HCC expressing CyK7 (CyK7-positive) and in HCCs CyK7-negative. Study Design: This study included 15 HCC CyK7-positive and 18 HCC CyK7-negative from patients submitted to LTx for HCV-related cirrhosis at the Niguarda Hospital in Milan. All specimens were stained with hematoxylin-eosin and immunohistochemically for CD34 to assess the degree of sinusoidal capillarization, reticulin to assess the cell plate architecture and Ki67 to identify neoplastic cells that are actively dividing. We generated a computerized morphometric model to evaluate the volume fractions occupied by hepatocyte nuclei and cytoplasm, sinusoids, portal triads, capillarised sinusoids and tumor cells actively dividing. Lastly, the surface fraction occupied by reticulin was calculated. Moreover, tumor cells expressing both CyK7 and Ki67 in HCC CyK7 positive were also identified. Ten high-grade dysplastic nodules from resection specimens of HCV-related cirrhotic livers were also used as control group. Results: On H&E stains, the features most discriminatory between HCCs CyK7-positive and CyK7-negative were volume fractions of sinusoids and of fibrosis and inflammatory infiltrate, which were significantly highest in HCCs CyK7-positive. On immunohistochemistry, volume fractions of capillarised sinusoids and of Ki67 cells were significantly highest in HCCs CyK7-positive. Conclusion: Our morphometric model is an objective method of quantification of the morphologic features in both CyK7-positive and CyK7-negative HCCs and it could be applied in studies involving histological evaluation of the different subtypes of HCC arising in the cirrhotic liver according to their CyK7 expression.