Comparison of Clinical Features and Outcome of Pediatric Posttransplant Lymphoproliferative Disorder in Recipients of Small Bowel Allograft Versus Isolated Liver Transplantation

Background. Higher incidence of posttransplant lymphoproliferative disorder (PTLD) is reported in the pediatric small bowel transplant (SBTx) population, which may be associated with more aggressive disease and poorer outcome as compared to liver transplant (LTx) recipients. We aim to compare the characteristics and outcome of PTLD in pediatric SBTx against LTx patients at a single center. Methods. Retrospective review of pediatric SBTx and LTx patients diagnosed with PTLD from 1989 to 2016 was conducted. Diagnosis of PTLD was biopsy-proven based on World Health Organization histologic criteria. Treatment protocol consisted of reduction of immunosuppression (RIS), rituximab (from 2000), cytotoxic T-lymphocyte (CTL) therapy (available in 1999-2004 and from 2011), and chemotherapy. Results. Thirty-seven PTLD patients were included following LTx (n = 23, incidence = 2.8%) and SBTx (n = 14, incidence = 14.9%). Monomorphic PTLD made up 64% of SBTx and 43% of LTx cases. RIS alone resulted in remission in 50% of LTx patients but none of the SBTx patients (P= 0.002). Poorer overall remission (57% versus 96%,P= 0.004), 2-year (46% versus 91%,P= 0.003), and 5-year survival rates (39% versus 90%,P= 0.002) were observed in the SBTx group. Risk factors associated with mortality following PTLD were SBTx (odds ratio [OR], 12.00; 95% confidence interval [CI], 2.34-61.45;P= 0.003), monomorphic histology (OR, 10.63; 95% CI, 1.88-60.25;P= 0.008), multisite involvement (OR, 6.38; 95% CI, 1.35-30.14;P= 0.019), and tumor involvement of allograft (OR, 5.33; 95% CI, 1.14-24.90;P= 0.033). Introduction of CTL therapy was associated with improved survival. Conclusions. Majority of PTLD following pediatric SBTx are of monomorphic subtype and associated with poorer outcome as compared to LTx patients. RIS is inadequate as a single strategy in managing PTLD in SBTx and prompt escalation to rituximab and CTL is recommended.