Posttransplant lymphoproliferative disorder of the central nervous system.

Posttransplant lymphoproliferative disorder (PTLD) involves uncommon, severe complications following the transplantation of solid organs, bone marrow and stem cells. Despite comprising mainly lymphoid proliferations that are predominantly driven by lymphotropic Epstein-Barr virus (EBV) infections, PTLD often displays substantial morphologic heterogeneity that can pose diagnostic challenges. With the steady increase in transplantations accompanied by potent immunosuppressive therapy, it is important to heighten awareness of this entity among clinicians and pathologists. In comparison to systemic PTLD, cases that primarily manifest in the central nervous system (CNS) are reported to be more severe and to exhibit unique characteristics. So far, only isolated cases and small series have been reported describing CNS involvement in PTLD. In this article, we review the current knowledge, focusing on the histopathological features of primary CNS lymphoproliferative disorders following organ transplantation.