Infiltrating hepatocellular carcinoma: seeing the tree through the forest

Abstract

Introduction: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. It is traditionally difficult to cure, especially when discovered at later stages, making early diagnosis and intervention of paramount importance. HCC typically arises in the background of chronic liver disease and can have various morphologic appearances. One of the most difficult of these to recognize on early surveillance imaging is the infiltrative subtype, which can account for up to 13% of all HCC cases, and may be more closely associated with background hepatitis B infection.

Discussion: Certain imaging characteristics can provide vital clues, including differing signal intensity on the T1 and T2 sequences of magnetic resonance imaging (MRI) and the presence/appearance of portal vein thrombus. Owing to the diffuse and infiltrating properties of this tumor, surgical resection and transplantation are rarely if ever viable therapeutic options. Other forms of liver-directed therapy have been attempted with limited success, having minimal efficacy and high morbidity. To date, there is no data available to determine if the various HCC subtypes respond to systemic therapy differently, so this may be the most reasonable approach. Left untreated, observed patients commonly progress to hepatic failure fairly rapidly.

Conclusion: Infiltrative HCC can be extremely subtle, and therefore difficult to detect, especially in the background of cirrhosis. Providers caring for patients with hepatitis, chronic liver disease, and cirrhosis must be extremely vigilant in the evaluation of surveillance imaging in order to potentially discover this HCC subtype as early as possible and initiate a multidisciplinary treatment plan.

Fig. 1

Fifty-five-year-old woman with hepatitis C, cirrhosis, and hepatocellular carcinoma. Axial (a) and coronal (b) contrast-enhanced CT in the arterial phase shows a heterogeneously enhancing liver mass in the left hepatic lobe with ill-defined margins (arrows). There is enhancing tumor thrombus in the portal vein (arrowheads). Axial (c) and coronal (d) contrast-enhanced CT in the portal venous phase shows an infiltrative mass in the left hepatic lobe (arrows) with areas of washout consistent with hepatocellular carcinoma

Fig. 2

MR images of the same patient as above. a Axial T2-weighted fat saturation image shows subtle T2 hyperintense signal within the infiltrative HCC in the left hepatic lobe (arrows). b Axial precontrast T1-weighted GRE image shows corresponding low T1 signal in the left hepatic lobe tumor (arrows). c Axial postcontrast T1-weighted GRE image in the arterial phase shows heterogeneous enhancement (arrows). d Axial postcontrast T1-weighted GRE image in the portal venous phase demonstrates patchy areas of washout within the tumor (arrows). e Axial diffusion-weighted MRI image shows restricted diffusion within the tumor (arrows)

Fig. 3

Fifty-three-year-old man with alcoholic cirrhosis and hepatocellular carcinoma. Axial contrast-enhanced CT in the arterial phase shows thrombus in the right portal vein (arrowheads). Small enhancing vessels seen within the thrombus indicate the presence of tumor. The infiltrative HCC (arrows) in the right hepatic lobe is difficult to appreciate. Stigmata of portal hypertension are seen, including ascites and caput medusa

Fig. 4

Fifty-three-year-old man with hepatitis C, cirrhosis, and hepatocellular carcinoma. Axial (a) and coronal (b) contrast-enhanced CT in the portal venous phase shows expansion of the portal vein with tumor thrombus (arrowheads). The branching low attenuation structures in the right hepatic lobe represent dilated tumor-filled peripheral portal vein branches (arrow in a)

Fig. 5

Sixty-six-year-old man with infiltrative hepatocellular carcinoma. a Axial contrast-enhanced CT in the arterial phase shows early enhancement or “arterializations” of the left portal vein (arrow) indicating tumor involvement. b Axial contrast-enhanced CT in the portal venous phase demonstrates tumor thrombus in the left portal vein as a low attenuation filling defect (arrow)