Early stage hepatocellular carcinoma detected during intraoperative ultrasonography

Recently, it has been recognized that there are increasing incidences of hepatocellular carcinoma (HCC) multicentricity. Thus, intraoperatively detected hepatic lesions that were once thought to be metastatic lesions now need to be carefully reexamined to determine whether they are true metastatic lesions or the multicentric development of HCC.

We investigated the histological characteristics of small nodular lesions detected during intraoperative ultrasonography in 33 consecutive patients with small HCC who underwent laparotomy at our institution.

Fourteen nodular lesions were found incidentally in 10 of 33 patients (30.3%), and were classified into the following three groups: 11 nodules in nine patients (27.3%) were HCC, two nodules in two patients (6.1%) were hemangioma, and one nodule in one patient (3.0%) was a large regenerative nodule. HCC therefore comprised 78.6% of the intraoperatively detected nodular lesions. Of the 11 HCCs, six were hyperechoic, four were hypoechoic, and one was isoechoic. Five (83.3%) of six small hyperechoic HCCs and two (50.0%) of four hypoechoic HCCs were well differentiated and retained their preexisting liver structure. These findings closely coincide with the characteristics of early stage HCC. Thus, early stage HCC comprised 63.6% of the intraoperatively detected HCC cases.

A certain proportion of small satellite HCCs detected during intraoperative ultrasonography in patients with small HCC, which were previously thought to be metastatic lesions from the main HCC, may instead be early stage HCCs. Such findings would also support the concept of the multicentric development of HCC. Approximately 60% of all small HCC cases detected intraoperatively may be early stage HCC. As a result, it is predicted that the emergence of HCC is either multicentric or unicentric, with early intrahepatic spread, although the former seems to be more common.