Case 341:   Focal Nodular Hyperplasia (FNH)

Diagnostic Category:

Clinical Presentation:

47 year old woman with history of dermatofibrosarcoma of the groin and liver lesion on imaging done for staging.

MR: Prominent fibrotic components

Imaging Findings:

MR with extracellular contrast agent shows biopsy proven focal nodular hyperplasia in segment 5/8 that is slightly hypointense on unenhanced T1 with more hypointensity centrally and mild hyperintensity on the T2w image.  It does not show fat components or restricted diffusion. Upon contrast administration, the lesion is hypervascular with thin hypovascular septations that gradually enhance to the equilibrium phase. Note slowly enhancing (hypovascular) lateral portions of the FNH are the only areas of the lesion that are seen on the portal venous phase. Late enhancement on equilibrium phase is due to presence of fibrotic components. No discernible central scar. Compare to CT.