FNH predominantly occurs in young females and MRI is the diagnostic modality of choice. The typical features at MRI include homogeneously isointense or slightly hyperintense tissue on T2 weighted images, the presence of a central stellate area, pronounced enhancement of the lesion in the arterial phase, accumulation of gadolinium chelates within the central scars on delayed T1 weighted images, and absence of tumour capsule.1
The central scar, which may not be seen in imaging studies, typically consists of fibrous connective tissue, cholangiocellular proliferation with inflammatory infiltrates and malformed vessels, including tortuous arteries, capillaries and veins,2
as shown in .
FNH is rare in men and the lesions are usually smaller and more often atypical (for example, no central stellate area on MRI, over high/low or heterogeneous signal intensity on T2 weighted images) than those in women (72.2% vs 16.7%),3
which may pose diagnostic difficulty as in our case. Hepatocellular carcinoma can be presented with a central scar in non-cirrhotic patients but usually occurs in their 60s.4
Fibrolamellar carcinoma is a large slow growing tumour which occurs at a young age with low AFP values and a normal liver, and could also present with central scars.5
Resovist enhanced MRI may be helpful to differentiate benign lesions from malignant ones.6
Practically speaking, if the lesion is small and all other tests are negative, a follow-up MRI scan in 3–6 months to assess for growth may be all that is required, particularly if a central scar is seen on MRI that is compatible with FNH.7
The enlarging hepatic tumour together with atypical MRI features in this patient, however, makes malignancy likely, and therefore justifies surgical resection and further pathologic confirmation.
- Focal nodular hyperplasia is rare in men and more often presents as atypical imaging features (no central stellate area on MR images, over high/low or heterogeneous signal intensity on T2 weighted images) than in women.
- Central scars can appear in both benign and malignant diseases such as focal nodular hyperplasia, fibrolamellar carcinoma or hepatocellular carcinoma.
- If in doubt, pathologic confirmation of liver tumours with suspicious malignant behaviours is warranted.