%0 Journal Article
%T Posttransplant Lymphoproliferative Disorders
%A Hazem A. H. Ibrahim
%A Kikkeri N. Naresh
%J Advances in Hematology
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/230173
%X Posttransplant lymphoproliferative disorders (PTLDs) are a group of diseases that range from benign polyclonal to malignant monoclonal lymphoid proliferations. They arise secondary to treatment with immunosuppressive drugs given to prevent transplant rejection. Three main pathologic subsets/stages of evolution are recognised: early, polymorphic, and monomorphic lesions. The pathogenesis of PTLDs seems to be multifactorial. Among possible infective aetiologies, the role of EBV has been studied in depth, and the virus is thought to play a central role in driving the proliferation of EBV-infected B cells that leads to subsequent development of the lymphoproliferative disorder. It is apparent, however, that EBV is not solely responsible for the ¡°neoplastic¡± state. Accumulated genetic alterations of oncogenes and tumour suppressor genes (deletions, mutations, rearrangements, and amplifications) and epigenetic changes (aberrant hypermethylation) that involve tumour suppressor genes are integral to the pathogenesis. Antigenic stimulation also plays an evident role in the pathogenesis of PTLDs. Plasmacytoid dendritic cells (PDCs) that are critical to fight viral infections have been thought to play a pathogenetically relevant role in PTLDs. Furthermore, regulatory T cells (Treg cells), which are modulators of immune reactions once incited, seem to have an important role in PTLDs where antigenic stimulation is key for the pathogenesis. 1. Introduction Post-transplant lymphoproliferative disorders (PTLDs) are a group of diseases that range from benign polyclonal to malignant monoclonal lymphoid proliferations. They develop as a consequence of immunosuppression. PTLDs are characterised by the following: they are usually derived from B cells with preferential presentation as non-Hodgkin¡¯s lymphoma (as against Hodgkin¡¯s lymphoma), usually originate in extranodal sites, rarely affect skin, behave aggressively, and frequently harbour the Epstein-Barr virus (EBV) genome. Whilst most are high-grade B-cell non-Hodgkin¡¯s lymphoma (NHLs), a few are classical Hodgkin¡¯s lymphomas. Rare cases have also been shown to be either of T-cell or NK-cell lineages [1, 2]. T-cell neoplasms constitute 10% to 15% of all PTLDs, and about 75% of T-cell PTLDs, have been shown to be negative for EBV and to behave more aggressively. T-PTLDs usually develop later than B-PTLDs and patients are less likely to respond to reduction in immunosuppression [3, 4]. The abnormal B cells in solid organ transplant recipients originate usually from those of the recipient, while in recipients of bone marrow
%U http://www.hindawi.com/journals/ah/2012/230173/