RESUMEN
<p><b>OBJECTIVE</b>To study the clinical and pathologic features of post-transplant lymphoproliferative disorders (PTLD), and to investigate the clinical significance of this diagnosis.</p><p><b>METHODS</b>Four cases of PTLD were studied by routine light microscopy, immunohistochemistry and in-situ hybridization and polymerase chain reaction. The clinical data and follow-up information were also reviewed.</p><p><b>RESULTS</b>In the 4 cases, 3 cases occurred in renal transplant recipients and 1 in bone marrow transplant patient. In the 3 post-renal transplant patients, 2 had polymorphic PTLD and 1 had monomorphic PTLD. The post-bone marrow transplant case was classified as "early" lesion of PTLD. Epstein-Barr virus (EBV) was detected in 2 cases. All the 4 cases studied had received cyclosporine A and steroids after transplantation. The duration between organ transplantation and diagnosis of PTLD from case 1 to case 4 was 42, 7, 129, 2 months. One of the polymorphic PTLD cases belonged to clinical stage II and subsequently died of the disease. Other cases belonged to clinical stage I and were alive for 5 to 40 months after diagnosis of PTLD.</p><p><b>CONCLUSIONS</b>PTLD is a lymphoproliferative disease with distinctive morphologic and clinical characteristics. An association with EBV at least in some cases is observed. The prognosis of PTLD correlates with clinical stage. It may respond to reduction in dosage of immunosuppressive agents.</p>