Growth patterns and interstitial invasion of small hepatocellular carcinoma

Twenty-five caw of small hepatocellular carcinoma (HCC; dhmeter ≥30mm) were evaluated for overall morphologic features and growth patterns. The tumors often showed a uelldtfferentlated, normotrabecular histologic pattern and insidious interstitial invasion, which resembled benign hepetocytes scattered in connective tissues. As the tumor grew, B less-differentiated tumor area became predominant. Portal tracts Included in small HCC nodules were quantitatively assessed, revealing that they progressively reduced in number with tumor growth. The tumor margin was often reported to be unclear. The present results indicate that the histologk grade of tumor differentiation, capsular formation, existence of liver cirrhosis and patterns of interstitial invaslon are important factors for determining the nature of the margin. The score of argyrophilic nuclear organizer regions (AgNOR) was examined in 5 cases showing typical interstitial imaslon with the insidious type. In each case, the AgNOR score of the invading tumor cells was lower than that of turnor cells within the HCC nodules, but higher than benign hepatocytes in cirrhotic parenchyma. It clarified that the growth activity of well-differentiated HCC was rather suppressed upon their interstitial invasion.