Infiltrative (sinusoidal) and hepatitic patterns of injury in acute cellular rejection in liver allograft with clinical implications.

Acute cellular rejection post liver transplant occurs most commonly but not exclusively in the first year. In this study, we report two patterns: sinusoidal infiltrative and hepatitic, which are not considered in the Banff system. We describe their presentation, response to Solu-Medrol, and compare these to the typical moderate-severe acute cellular rejection. Patients transplanted from 2007 to 2012 at University Health Network, who had biopsy-proven rejection in the first year, were studied. Baseline transaminases and bilirubin, time of acute cellular rejection, follow-up, and treatment responses were analyzed. A total of 407 biopsies were received, of which 77 had diagnosis of acute cellular rejection with rejection activity index 5 or above; 49 from viral hepatitis patients were excluded. Twenty-eight were included; 15/28 (54%) had typical acute cellular rejection (tACR) using Banff criteria. Six (21%) had hepatitic acute cellular rejection overlapping with typical features of acute cellular rejection; seven (25%) had infiltrative acute cellular rejection (iACR) overlapping with typical features. The iACR occurred later than the tACR (124 versus 50 days; P = 0.032) and had a higher rise in baseline aspartate aminotransferase (ΔAST) compared with tACR (289 U/l versus 109 U/l; P=0.046). Only one out of seven patients with iACR (14 versus 40% in tACR) failed Solu-Medrol boluses and required thymoglobulin. Patients with hepatitic acute cellular rejection (hACR) had similar ΔAST (P = 0.12) but higher bilirubinemia than typical acute cellular rejection (tACR) (160 μmol/l versus 35 mol/l; P = 0.039) and required thymoglobulin in four out of six (67% versus 40%) instances. Patients with iACR had higher ΔAST than tACR but better Solu-Medrol response compared with both tACR and hACR. hACR is different from plasma cell-rich late-occurring cellular rejection in its pattern but similar in its poor Solu-Medrol response.