LI-RADS 3 lesion

Case contributed by Dr Matt A. Morgan

Presentation

History of hepatitis C cirrhosis. The patient received TACE for a probable HCC in the left hepatic lobe. The current MRI is a screening exam, the prior MRI was 3 months prior.

Patient Data

Age: 54Y
Gender: Male
MRI

Multiple new small (8 mm) nodular hypervascular lesions are present in the right hepatic lobe on the arterial phase (red arrows). On the portal venous phase, these lesions fade to background liver enhancement. There is no capsule around any lesion.

On the T2W sequence (not shown), these lesions cannot be discretely identified in the setting of diffuse fibrotic change from cirrhosis. There is no restricted diffusion.

Nodular liver surface is compatible with cirrhosis. No evidence of portal hypertension.

The left hepatic lobe lesion treated with TACE (not shown) is similar in size and appearance to 3 months ago.

Case Discussion

LI-RADS is a classification system for communicating the likelihood of a hepatic lesion being hepatocellular carcinoma (HCC) in an at-risk liver. Like BI-RADS for breast imaging, the idea of the classification system is to take a wide variety of possible findings on CT or MRI and condense them into prognostic and treatment groups that will not vary as much from institution to institution.

The lesions in this case would be defined as LI-RADS 3 lesions, which is classified as "indeterminate probability for HCC". The lesion shows arterial phase hypervascularity, but only measures 8 mm and does not fulfill any of the major criteria to make it a level 4 or 5:

  • no "washout"
  • no presence of an enhancing "capsule" (pseudocapsule)
  • no interval growth (a new lesion <10 mm is not considered "interval growth")

These likely represent small dysplastic nodules, and their absence on the prior study 3 months ago makes them indeterminate. The lesion in the left hepatic lobe treated with TACE (not shown) had a very similar appearance, but also demonstrated convincing washout, so was considered "probably HCC". Another possibility is that these lesions represent small arterioportal or arteriovenous shunts, but in this particular setting, the lesions are nodular-appearing and not morphologically obvious as shunts. A small nodular region of transient vascularity would not be incompatible with a small tumour.

Either way, follow up is a relatively safe approach in this at-risk patient. Because they are LI-RADS 3 lesions, biopsy is unnecessary. Since they are indeterminate, they should be followed up per the local protocol.

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Case information

rID: 33880
Case created: 28th Jan 2015
Last edited: 7th Dec 2017
Inclusion in quiz mode: Included

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