American Board of Pathology (ABPath) Practice Test

Focal nodular hyperplasia (FNH) of the liver is characterized by a specific imaging finding known as the "stellate star sign." This appearance is typically identified on cross-sectional imaging modalities like computed tomography (CT) or magnetic resonance imaging (MRI). The stellate star sign refers to the radiological appearance of a central scar that radiates out in a star-like pattern, surrounded by hyperplastic liver tissue. This central scar is a hallmark feature of FNH and helps differentiate it from other hepatic lesions, such as hepatic adenoma or liver metastases.

The central scar may be better appreciated using MRI with contrast, where the lesion demonstrates unique enhancement patterns. FNH typically demonstrates hypointense characteristics in T1-weighted images and hyperintense characteristics in T2-weighted images, further supporting its identification through imaging.

Other imaging findings listed are associated with different pathologies: the "starry sky sign" is often linked to Burkitt lymphoma, "ground glass opacity" is associated with certain types of pulmonary pathology, and the "bull's eye lesion" may refer to other focal liver lesions or conditions. Each of these signs is pathognomonic or characteristic of different conditions and not directly relevant to FNH. Understanding these distinctions