Lipiodol-CT for hepatocellular carcinoma

Abstract

Lencioni et al. have nicely presented a positive predictive value of Lipiodol CT for intrahepatic metastasis of hepatocellular carcinoma (HCC) based on 32 consecutive patients undergoing hepatectomy [1]. Lipiodol-CT has been generally regarded as a highly sensitive examination to detect intrahepatic metastases because these mostly occur in hypervascular HCC (advanced or classic HCC, histopathologically moderately or poorly differentiated) and have a similarly hypervascular character. However, there has been no direct confirmation of high sensitivity and specificity by this method. Theoretically and clinicopathologically, Lipiodol is distributed in loci according to their vascularity. Long-term deposits are noted in the necrotic area of the tumor and liver parenchyma, especially after embolization [2]. Thus, any hypervascular nodular lesion such as small cavernous hemangioma and focal nodular hyperplasia and nontumorous area such as focal inflammation and arterioportal shunt could be false-positive cases of intrahepatic metastasis, although the durations of deposit are different case by case [2]. Such cases have been sporadically reported [3, 4]. Lencioni et al. have defined a positive finding of intrahepatic metastasis at Lipiodol-CT as a small, rounded, well-delineated retention less than 2 em in diameter but have not described any pathologic definition or finding. In general, intrahepatic metastases are present in cases with HCC associated with portal tumor thrombus, multiple in number, small in size, and located adjacent to the main tumor [5]. However, intrahepatic metastasis is not a self-evident lesion, especially in patients at high risk for HCC who often have multicentricoccurring tumors of different or same subtype. Even when using DNA analysis, pathologists cannot necessarily confirm whether or not a particular lesion is an intrahepatic metastasis [5, 6].