Pathological study on multicentric occurrence of hepatocellular carcinoma.

Recently, it has been suggested that many of hepatocellular carcinoma (HCC) are of multicentric origin based on the clinicopathologic studies on small HCCs of the early stage and clinical follow-up studies after successful treatments of small HCCs. The author studied the multicentric occurrence of HCC from the point of view of pathomorphology in 168 HCCs less than 3 cm in diameter consecutively resected from 1999 to 2004 and 8 autopsy of liver cirrhosis of micronodular type from 1990 to 2004 at Kurume University Hospital from 1999 to 2004. The association of well-differentiated HCC ranging from 9 mm to 1.2 cm in diameter was found in the non-cancerous tissue of 9 cases (9.5%) among 94 cirrhotic livers. Adenomatous hyperplasia (AH) was found in 7 cases (7.4%). Accordingly, prevalence of synchronous and metachronous multicentric hepatocarcinogenesis was highly suggested in 9.5% and 7.4%, respectively. In 4 (50%) of the 8 autopsy cases of micronodular cirrhosis, however, the coexistence of 2 well-differentiated HCCs around 1.5 cm were found in the different segment. The prevalence of multicentric occurrence in the resected cases is the lowest estimation and true prevalence should be much more higher because HCC cases with multiple nodules are not sent to surgery and the observation is limited in a small area of the subsegmentectomized liver. Indeed, the result of autopsy cases reflects a true prevalence (50%) of synchronous occurrence of HCC.