Isolated vascular "v" lesions in liver allografts: How to approach this unusual finding.

According to the Banff criteria for kidney allografts, isolated vascular or "v" lesions are defined as intimal inflammation, age-inappropriate fibro-intimal hyperplasia, or both, without the presence of associated interstitial T cell-mediated rejection (TCMR). In general, these lesions portend a worse outcome for kidney allografts, particularly in those where the "v" lesions are identified in patients with coexistent donor specific antibodies (DSA) or later after transplantation. Although affected arteries are rarely sampled in liver allograft biopsies, we identified nine patients at a mean of 1805 days posttransplantation and compared these to matched controls. Almost half (4 of 9) of the study patient biopsies showed inflammatory arteritis associated with focal or diffuse C4d positivity, which was not observed in matched controls. One "v" lesion patient progressed to rejection-related graft failure and two developed moderate/severe TCMR in subsequent biopsies, whereas only one rejection episode occurred in follow-up biopsies, and no rejection-related deaths or graft failures were detected in controls. In conclusion, patients with liver allograft isolated "v" lesions should undergo further evaluation and closer follow-up for impending TCMR and/or underlying co-existent chronic antibody-mediated rejection (AMR).