Small hepatocellular carcinomas and associated nodular lesions of the liver: pathology, pathogenesis, and imaging findings.

Hepatocellular carcinomas frequently occur in association with liver cirrhosis, as chronic liver disease is one of the most important factors in carcinogenesis. In addition to small hepatocellular carcinomas (less than 3 cm in diameter), recent reports of pathologic studies of resected specimens from cirrhotic liver describe associated small nodular lesions (i.e., regenerating nodule, adenomatous hyperplasia, and early hepatocellular carcinoma). In hepatocarcinogenesis of the cirrhotic liver, a regenerating nodule might be the first step in the development of hepatocellular carcinoma, going through phases of adenomatous hyperplasia and early hepatocellular carcinoma in a multistep fashion. We describe the pathologic characteristics of small hepatocellular carcinomas and associated nodular hepatic lesions and review the current concepts of the role of these associated lesions in carcinogenesis. We also discuss the imaging findings of these abnormalities, the efficacy of various imaging techniques for diagnosing them, and the importance of imaging in treatment planning.