Description:
<jats:sec><jats:title>Aims</jats:title><jats:p>The aim of this study was to perform a comprehensive retrospective analysis of liver transplant biopsies with parenchymal rejection (<jats:roman>PR</jats:roman>) at our institution, including histological features, laboratory values and follow‐up biopsies, and to compare <jats:roman>PR</jats:roman> with portal‐based acute cellular rejection (<jats:roman>ACR</jats:roman>).</jats:p></jats:sec><jats:sec><jats:title>Methods and results</jats:title><jats:p>Biopsies from 173 patients were evaluated (retrospective database search 1990–2017), including 49 isolated <jats:roman>PR</jats:roman>, 35 <jats:roman>PR</jats:roman> with portal <jats:roman>ACR</jats:roman> (<jats:roman>PR</jats:roman>/<jats:roman>ACR</jats:roman>), 34 mild <jats:roman>ACR</jats:roman> and 52 moderate <jats:roman>ACR</jats:roman> cases. The rise and fall of serum liver enzymes was calculated as a measure of acute liver injury and response to immunotherapy, respectively. Isolated <jats:roman>PR</jats:roman> was associated with delayed‐onset acute rejection (<jats:italic>P</jats:italic> < 0.001), as well as younger age (<jats:italic>P</jats:italic> = 0.004), and showed a similar rise in liver enzymes to mild <jats:roman>ACR</jats:roman>. <jats:roman>PR</jats:roman>/<jats:roman>ACR</jats:roman> and moderate <jats:roman>ACR</jats:roman> showed the highest elevations in transaminases (<jats:italic>P</jats:italic> < 0.05). Isolated <jats:roman>PR</jats:roman> on an initial biopsy was associated with recurrent episodes of <jats:roman>PR</jats:roman> (<jats:italic>P</jats:italic> = 0.01), chronic ductopaenic rejection (<jats:italic>P</jats:italic> = 0.002) and chronic vascular rejection (<jats:italic>P</jats:italic> = 0.017). Immunohistochemistry for C4d was performed, and strong C4d staining of venules was only detected in one severe isolated <jats:roman>PR</jats:roman> case (one of three, 33%) and one moderate <jats:roman>ACR</jats:roman> case (one of 20, 5%).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Isolated <jats:roman>PR</jats:roman> represents a form of late acute rejection with distinct clinical and histological features. There is value in reporting <jats:roman>PR</jats:roman> in liver transplant biopsies to identify patients at higher risk of developing recurrent <jats:roman>PR</jats:roman> and chronic rejection. Standardisation of terminology and histological criteria of <jats:roman>PR</jats:roman> can help in uniform reporting and ensure appropriate management.</jats:p></jats:sec>