Hepatic focal nodular hyperplasia (FNH) is a benign hepatic tumor. FNH develops within hepatic parenchymal tissue that is otherwise histologically normal. Macroscopically, the tumor is characterized by the presence of depressed, grayish-white scar, which is generally (but not always) located at the center of the lesion, with fibrous septa radiating outward, toward the periphery of the tumor. This stellate scar is found in only 50% of all FNH nodules, but its presence is regarded as pathognomonic. The lesion itself is usually lighter in color than the tissue that surrounds it, and it sometimes has a yellowish hue. FNH nodules are generally not capsulated; their margins are well defined, and they are sometimes lobulated. [from
HPO]