Post-transplant lymphoproliferative disorders.

Post-transplant lymphoproliferative disorder (PTLD) is one of the most dreaded complications of orthotopic transplantation. It consists of a heterogeneous group of lymphoproliferative disorders of varying clonal composition, occurring in immuno-suppressed organ allograft recipients and is frequently due to EBV infection. It is most common in heart/lung transplants followed by heart, liver, and kidney and rarely in bone marrow transplants. Clinically, PTLD can present in a number of ways ranging from features resembling infectious mononucleosis, lymphoproliferative masses involving both nodal and extranodal locations, to a fulminant form characterized by a combination of peripheral lymphadenopathy, severe metabolic acidosis, organ failure or allograft dysfunction. Pathologically PTLD is characterized by a dense inflammatory infiltrate with a spectrum ranging from that found in infectious mononucleosis to a polymorphous B-cell hyperplasia to that of a monomorphous lymphoma. Analysis of EBV is especially useful for the diagnosis of early cases of PTLD. In addition, immunophenotyping to determine the lymphocyte type (B or T cell type) and monoclonality are most helpful in determining the prognosis.