Infiltrative hepatocellular carcinoma (HCC), also known as diffuse hepatocellular carcinoma, is an infrequent subtype of HCC, which has particular imaging characteristics. Because of these characteristics, it has been called cirrhotomimetic HCC or cirrhosis-like HCC.

Epidemiology

Infiltrative hepatocellular carcinomas account for ~15% (range 13-20%) or less of HCC cases and are reportedly often associated with hepatitis B ^ref.

Radiographic features

In contrast to the nodular or massive HCC subtypes, infiltrative HCC is ill-defined consisting multiple tiny liver nodules spreading throughout the entire liver or entire liver lobe, without a dominant nodule ^ref.

MRI is the modality of choice with regards to infiltrative hepatocellular carcinoma, since they may be subtle and difficult to differentiate from liver cirrhosis with other modalities ^ref.

MRI

Signal characteristics

• T1: homogeneously hypointense or heterogeneously hypointense in contrast to normal surrounding liver

• T1 C+ (Gd):

  • arterial phase

    • in contrast with typical hepatocellular carcinoma, it shows minimal arterial enhancement, hypoenhancement or isoenhancement

    • a miliary pattern of enhancement has also been reported

  • venous and delayed phases

    • washout remains a feature of infiltrative HCC, although it may be more heterogeneous or irregular than its nodular counterpart

    • washout may be absent in up to 50% of cases, in contrast to 33% of nodular hepatocellular carcinoma ³

    • a reticular appearance of the tumor can be seen, possibly related to fibrosis

• T2: usually appears slightly hyperintense in comparison to normal surrounding liver

• DWI: may appear slightly hyperintense to normal surrounding liver

Malignant portal vein thrombosis is often seen with infiltrative hepatocellular carcinomas and sometimes may be mistaken as the only radiological finding due to:

• the enhancement of the main infiltrative lesion being rather subtle

• the associated liver perfusion changes may complicate the imaging interpretation

Treatment and prognosis

Infiltrative HCC carries a worse prognosis than the nodular subtype ^1,4.

Differential diagnosis

The differential diagnosis of infiltrative hepatocellular carcinoma is different from that of "regular" hepatocellular carcinoma because of its conspicuous appearance. Main differential diagnoses include:

• diffuse liver metastasis

• pseudocirrhosis

• diffuse liver microabscesses

• confluent liver fibrosis

See also

• hepatocellular carcinoma

• hepatocellular carcinoma staging

• LI-RADS