Patient 8, periphery of nodule a (subtle FNH): types 2, 3, and 4 lesions (a, b, c); patient 4, periphery of nodule b: type 4 lesion (d). (a, b, c, d) The limit of the nodule is hard to define. In (a) and (b), steatosis is present outside the nodule; in (c), there is a thick band of collagen which contains abnormal vessels; in (d), the limit lies between the hepatic vein (HV) and the course of the arterioles (arrow). In (a), between the hepatic vein (HV) and the fibrous band of the subtle lesion of FNH (arrowhead), the rim of parenchyma looks superficially normal; however, it contains many isolated arteries (arrow). In (b, and d), regions of dilated sinusoids with compressed hepatocytes lie between hyperplastic foci (HF) with obvious or no ductular reaction. In (c), outside the limit of the subtle lesion of FNH, a region of sinusoidal dilatation is present, with peliosis encircling a hyperplastic focus (HF) beneath the fibrotic band. All, H&E.