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Understanding the important alterations during hepatocarcinogenesis as well as the characteristic magnetic resonance imaging (MRI) and histopathological features will be helpful for managing patients with chronic liver disease and hepatocellular carcinoma. Recent advances in MRI techniques, such as fat/iron quantification, diffusion-weighted images, and gadoxetic acid-enhanced MRI, have greatly enhanced our understanding of hepatocarcinogenesis.
Key Words: Hepatocarcinogenesis; Magnetic resonance image; Carcinoma, hepatocellular; Pathology
Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the third most common cause of death from cancer.1 Asia is an endemic area of HCC. It is estimated that approximately 75%-80% of the HCC cases worldwide develop in Asia.2 The primary etiological factor in Asia is the hepatitis B virus; however, the proportion of hepatitis C virus-related HCC has been increasing.3 In chronic hepatitis B or C, multistep hepatocarcinogenesis, in which dysplastic nodules progress to early HCC and eventually advanced HCC, is widely accepted as the main mechanism of HCC development.4
Knowledge of the mechanism of hepatocarcinogenesis is important, as it may contribute to improved detection of HCC at an early stage and more successful therapeutic outcomes. In fact, the 5-year survival rate for patients with HCC has improved over the past several decades, and the early detection of HCC is one of the most important contributing factors.5 In particular, the nationwide surveillance for HCC among high-risk individuals has allowed small HCCs less than 2 cm in diameter to be easily detected.4 Furthermore, the rapid development of noninvasive imaging technology, including the rapidly developing, high-quality magnetic resonance (MR) techniques using new, cell-specific contrast agents, may allow further improvement of the detection and characterization of small nodules in cirrhotic livers.6 As a result, we are currently able to diagnose more earlystage HCCs. Pathologists and radiologists should be aware of the variable imaging features of these early-stage HCCs, as they frequently show different characteristics than advanced HCC. In this study, we review the important changes in magnetic resonance imaging (MRI) and histopathologic features during multistep hepatocarcinogenesis as well as the recent developments in MRI technology for detecting and characterizing hepatocellular nodules.
MULTISTEP HEPATOCARCINOGENESIS: HISTOLOGIC CHANGE
Multistep hepatocarcinogenesis is characterized by progressive dedifferentiation of phenotypically abnormal nodular lesions in the liver and the emergence of successively more advanced precancerous, early cancerous, and overtly...