Focal nodular hyperplasia (FNH) is a benign tumour of the liver (hepatic tumour), which is the second most prevalent tumour of the liver (the first is hepatic hemangioma). It is usually asymptomatic, rarely grows or bleeds, and has no malignant potential. This tumour is often resected because it is difficult to distinguish from hepatic adenoma.
Focal nodular hyperplasia’s most recognizable gross feature is a central stellate scar seen in 60-70% of cases. Microscopically, a lobular proliferation of bland-appearing hepatocytes with a bile ductular proliferation and malformed vessels within the fibrous scar is the most common pattern. Other patterns include telangiectatic, hyperplastic-adenomatous, and lesions with focal large-cell dysplasia. Rarely, these lesions may be multiple or can occur as part of a syndrome with hemangiomas, epithelioid hemangioendothelioma, hepatic adenomas, fibrolamellar hepatocellular carcinoma, vascular malformations of the brain, meningiomas, and/or astrocytomas.
No focal lesion is seen in native CT
Typical central scar
Vascular filling of the central scar