Atrophic hepatocytes express keratin 7 in ischemia-associated liver lesions

Abstract

Aim: To investigate atrophic parenchymal changes in ischemic liver conditions. Design: We studied 18 cases of hepatic lesions with atrophic changes due to altered blood flow (hepatic venous congestion n=15 including 4 cases with additional nodular regenerative hyperplasia-NRH, NRH n=1, and antiphospholipid syndrome with patchy parenchymal atrophy n=2). Metaplastic hepatocellular changes, hepatocyte proliferation, hepatic stellate cell (HSC) activation, and sinusoidal capillarization were examined immunohistochemically with antibodies to keratins (K) 7 and 19, Ki67, αSMA and CD34, respectively. Results: K7 was positive and K19 was negative in zone 3 atrophic hepatocytes in venous congestion and in areas of plate atrophy, as well as in congested or compressed sites in NRH. Sinusoidal CD34-positivity indicating capillarization accompanied K7 immunoexpression. Masson trichrome revealed sinusoidal fibrosis to be restricted in atrophic areas, usually mild and in 7 cases focally dense. αSMA expression expanded beyond K7- positive areas. Ki67 was negative in K7-positive hepatocytes. Conclusion: Ischemic parenchymal changes are characterized by hepatocyte K7 immunoexpression, sinusoidal capillarization, HSC activation and lack of cellular proliferation, indicating an early reaction of the major liver parenchyma cellular components creating a more resistant microenvironment. These phenotypic alterations may prove valuable in the discrimination of ischemic liver lesions.