Group of conditions that involve uncontrolled proliferation of lymphoid cells as a consequence of extrinsic immunosuppression after organ or haematopoietic stem cell transplant.
PTLD typically has a more rapid onset in HSCT patients, with median time of 4–6 months after transplant
WHO Classification of PTLD (2008):
Classical HL-type PTLD
Oligo- or polyclonal proliferation of EBV-positive B cells while the underlying tissue architecture is preserved.
Infectious mononucleosis-like lesions
Oligo- or polyclonal B-cell proliferation, but here, the infiltrating cells destroy the original architecture of the host tissue.
All PTLDs fulfilling the histopathologic criteria of “classical” non-Hodgkin’s lymphoma (NHL) are diagnosed according to the classification of nontransplant associated lymphomas.
B cell neoplasms:
Diffuse large B-cell lymphoma, (DLBCL)
Plasma cell myeloma
T cell neoplasms:
Peripheral T cell lymphoma
Not otherwise specified (NOS)
Classical HL-type PTLD & HL-like PTLD:
Classical Hodgkin’s disease and Hodgkin-like PTLD also belong to monomorphic PTLDs, but due to their special histological and clinical features, they represent a separate group within the WHO classification.
Associated EBV infection ((55–65%)
Degree of immunosuppression
Recipient age and race
Host genetic variations
Oncogenic Epstein–Barr virus (EBV): Key pathogenic driver in many early-onset cases, through multiple mechanisms.
In immunocompetent hosts, the EBV genome is immortalized, forming an episome in latently infected B cells. Immunosuppression leads to depressed T cell function with associated lack of T cell control of B cell proliferation; this results in uncontrolled proliferation of EBV-transformed B cells, which contributes to the development of PTLD.
Lymphadenopathy (often absent)
Usually due to interference with the function of involved organs.
Extranodal involvement (common): Gastrointestinal tract (GIT), lungs, skin, bone marrow (BM), and central nervous system (CNS)
BM involvement (rare)
Classic B symptoms:
Pyrexia, sweats, and weight loss
Reduction of immunosuppression (mainstay)
Rituximab (B cell-specific antibody against CD20) +/− combination chemotherapy