RESUMEN
INTRODUCTION: Posttransplant lymphoproliferative disorder (PTLD) constitutes a heterogeneous group of diseases. We summarize the experience of our hospital, one of Spain's largest series of renal (294), liver (47) and allogeneic stem cell transplants (67), where four cases of PTLD have developed related to complex viral infections. METHODS: Case 1 was a 24-month-old boy diagnosed with acute lymphoblastic leukemia who underwent allogeneic stem-cell transplantation (SCT). He was seropositive for Epstein-Barr virus (EBV) and developed an aggressive Bcell non-Hodgkin's lymphoma (B-NHL) related to EBV reactivation and human herpesvirus 6 (HHV-6) infection. Cases 2, 3, and 4 developed after kidney transplantation and were all EBV seronegative. Case 2 had associated cytomegalovirus (CMV) and EBV infection. Cases 3 and 4 only revealed EBV viral load. Cases 1, 3, and 4 progressed rapidly, with fatal outcome. Global incidence of PTLD in our series is 1.1%. CONCLUSION: PTLD is a rare but life-threatening condition. Although EBV plays a clear role in its pathogenesis, other associated viral infections could trigger this situation. Current therapies include rituximab, decreasing immunosuppressive drugs. and conventional chemotherapy.