Infiltrative hepatocellular carcinoma
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.
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 .
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.
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.
- T1: homogeneously hypointense or heterogeneously hypointense in contrast to normal surrounding liver
- T1 C+ (Gd):
- arterial phase
- in contrast with typical HCC, 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 49.2% of cases, in contrast to 32.6% of nodular HCC.
- a reticular appearance of the tumor can be seen, possibly related to fibrosis.
- arterial phase
- 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 HCCs and sometime may be mistaken as the only radiological finding due to:
- the enhancement of the main infiltrative lesion may be rather subtle
- the associated liver perfusion changes may complicate the imaging interpretation
The differential diagnosis of infiltrative HCC is different from that of regular HCC because of its conspicuous appearance. Main differential diagnoses include: