Identification of nodules of altered hepatocytes from focal nodular hyperplasia, with comparison to hepatocellular adenoma.

Abstract

Objective Focal nodular hyperplasia(FNH) is composed of multiple hyperplastic liver cell nodules,but its pathogenesis has not been elucidated. Foci (FAH) or nodules of altered hepatocytes (NAH) are precursors of hepatocellular adenoma (HCA) and carcinoma.This study aimed at identifying FAH and NAH from FNH and evaluating their role in FNH development.Methods 6 FNH lesions from 5 patients and 10 HCA from 9 patients were examined histologically,and expression levels of CD_(34) cytokeratin 19(CKl9) and Ki-67 antigen were demonstrated immunohistochemicailly.Proliferative activity was evaluated by Ki-67 antigen-labeling indices(Ki-67 LI).Results Multiple FAH and NAH were identified in all of the 6 FNH lesions. Whiie micmvasculatures were demonstrated by CD_(34) immunoreactivity in both HCA and FNH,their density and distribution were different in these two lesions,being diffuse in HCA and focal or nodular,mainly within NAH.CKl9 expression Was found in FNH,localized in ductal and ductular cells,but not within NAH and HCA.Average Ki.67 LI of 73 NAH(2.8%) was shown to be higher than that of the whole FNH lesions (0.6%),and had no statistieal difference comparable to that of HCA(1.8%).Conclusion Muhiple NAH are present in all classical FNH lesions.Unlike the surrounding parenchyma,NAH lesions are more proliferative and equipped with CD_(34)-positive microvasculatures as in HCA. Key words: Nodule of altered hepatocytes; Focal nodular hyperplasia; Microvascular density; Adenoma,liver cell