Hepatocarcinogenesis in liver cirrhosis: imaging diagnosis

Hepatocellular carcinoma (HCC) frequently occurs in association with liver cirrhosis, as chronic liver disease is one of the most important factors in carcinogenesis. In addition to HCCs, recent reports of pathologic studies of resected specimens from cirrhotic liver describe associated small nodular lesions such as regenerative nodule, dysplastic nodule (adenomatous hyperplasia), and dysplastic nodule with subfocus of HCC (early HCC). In hepatocarcinogenesis of the cirrhotic liver, a regenerative nodule might be the first step in the development of HCC, going through phases of dysplastic nodule, early HCC and early advanced HCC in a multistep fashion. Fortunately, recent advances in various imaging techniques have facilitated the verification of these nodules. In this review, new nomenclature of small hepatocellular nodules, and detection and characterization of hepatic nodules in carcinogenesis with various imaging techniques are described with focus on the premalignant lesions and early stage of HCC. In addition, the efficacy of various imaging techniques for diagnosing them is discussed. Although the terms and definitions of these nodules are still variable and controversial, familiarity with the concept of these borderline lesions is important.