Hepatic fibrosis and cirrhosis in the Fontan circulation: a detailed morphological study

Abstract

Aims: To describe the histological features of the liver in patients with a Fontan circulation. Methods: Liver biopsies carried out as part of preoperative assessment prior to extracardiac cavopulmonary conversion of an older style Fontan were examined and scored semi-quantitatively for pertinent histological features. To support the use of the scoring, biopsies were also ranked by eye for severity to allow correlation with assigned scores. Results: Liver biopsies from 18 patients with a Fontan circulation were assessed. All biopsies showed sinusoidal fibrosis. In 17/18 cases there was at least fibrous spur formation, with 14/18 showing bridging fibrosis and 2/18 demonstrating frank cirrhosis. In 17/18 cases at least some of the dense or sinusoidal fibrosis was orcein positive, although a larger proportion of the dense fibrous bands were orcein positive compared with the sinusoidal component. All biopsies showed marked sinusoidal dilation, and 14/18 showed bile ductular proliferation. 1/18 biopsy showed minimal iron deposition, 1/18 showed mild lobular lymphocytic inflammation. There was no cholestasis or evidence of hepatocellular damage. Similar appearances were observed in 2 patients with severe tricuspid regurgitation. Discussion: The histological features of the liver in patients with a Fontan circulation are similar to those described in cardiac sclerosis. Sinusoidal dilatation and sinusoidal fibrosis are marked in the Fontan series. The presence of a significant amount of orcein negative sinusoidal fibrosis suggests there may be a remediable component, although the dense fibrous bands are predominantly orcein positive suggesting chronicity and permanence. No inflammation or hepatocellular damage is evident, suggesting that fibrosis may be mediated by a non-inflammatory mechanism.