Introduction: Posttransplant lymphoproliferative disorders (PTLD) represent a heterogeneous group of lymphoid and plasmacytic proliferative diseases, occurring as a result of immunosuppressive therapy in patients who have received solid organ or bone marrow transplantation.  Only very few studies of kidney transplant recipients with PTLD were recruited from the Asian population, especially the Chinese patients and these data are usually restricted to small case series.  The objective of our study is to characterize the PTLD including the Epstein-Barr virus (EBV) status, histological subgroups, site of occurrence and the clinical outcome in the Chinese kidney transplant recipients.
Materials and Methods: A retrospective cohort study of 1,227 adult kidney transplant recipients who were followed up in two large transplant centers in Hong Kong between the period 1stJanuary 1994 and 30th June 2015 and were diagnosed to have PTLD.
Results: 23 (1.9%) patients developed PTLD.  Median duration from transplant to PTLD was 104 (5-252) months.  Six patients (26.1%) had early PTLD and 17 (73.9%) had late PTLD.  Ten (43%) developed PTLD >10 years after transplant.  All patients in early PTLD group were EBV-positive.  In the late PTLD group, 60% were EBV-negative and 40% EBV-positive.  More than 90% of cases were monomorphic PTLD with majority being diffuse large B cell lymphoma.  Lymph nodes were the most common location of PTLD (34.8%), followed by bone marrow (30.4%), brain and gastrointestinal tract (17.4%).  All patients except the one with nodal marginal zone lymphoma had extranodal involvement of PTLD.  More patients (16/23, 69.6%) presented with late-stage (III or IV) PTLD than early-stage disease (7/23, 30.4%) in our cohort.  The overall treatment response rate was 52.2 %.  None of the patients developed allograft rejection or relapse after complete remission of PTLD.  At a median follow-up of 9 (1-79) months after PTLD, 18 patients died.  Patient survival was 48% at 1 year and 30% at 3 years and death-censored allograft survival was 82% at 1year and 73% at 3 years.
Conclusion: Late PTLD is common. Careful adjustment of immunosuppression, close monitoring of patients, increased awareness and early detection of the disease are essential.