Infiltrative hepatocellular carcinoma, also known as diffuse hepatocellular carcinoma (HCC), 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.
Infiltrative HCCs account for 13-20% or less of HCC cases and is reportedly often associated with hepatitis B. Moreover, infiltrative HCC carries a worse prognosis than the nodular subtype 1,4.
MRI is the modality of choice with regards to infiltrative HCC, since they may be subtle and difficult to differentiate from liver cirrhosis with other modalities.
In contrast to the nodular or massive subtype of HCC, infiltrative HCC isn't well defined. It consists of multiple tiny liver nodules spreading throughout the entire liver or entire liver lobe, without a dominant nodule, and isn't as well defined as the other subtypes.
Malignant portal vein thrombosis is often seen with infiltrative HCCs and sometime may be mistaken as the only radiological finding, as the enhancement of the main infiltrative lesion may be rather subtle. Moreover, liver perfusion changes associated with portal venous thrombosis may complicate the imaging interpretation.
- T1: homogeneously hypointense or heterogeneously hypointense in contrast to normal surrounding liver
T1 C+ (Gd):
- arterial phase: hypervascular enhancement is usually minimal in contrast with typical HCC, and arterial hypoenhancement or isoenhancement may be seen; a miliary pattern of enhancement has also been reported
- venous and late enhancement phase: washout remains a feature of infiltrative HCC, although it may be more heterogeneous / irregular than its nodular counterpart
- it is worth noting that washout may be absent in up to 49.2% of cases, in contrast to 32.6% of nodular HCC 3
- T2: usually appears slightly hyperintense in comparison to normal surrounding liver
- DWI: may appear slightly hyperintense to normal surrounding liver
The differential diagnosis of infiltrative HCC is different from that of regular HCC because of its conspicuous appearance. Main differential diagnoses include:
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