Primary central nervous system posttransplant lymphoproliferative disorders.

Area of Science:

• Neuropathology
• Transplant Oncology
• Immunology

Background:

• Posttransplant lymphoproliferative disorders (PTLDs) encompass a range of lymphoid proliferations following transplantation.
• Central nervous system (CNS) PTLDs are less understood compared to PTLDs in other organs.
• PTLDs can be Epstein-Barr virus (EBV)-driven or EBV-negative, ranging from polyclonal to malignant lymphomas.

Purpose of the Study:

• To fully characterize primary CNS PTLDs.
• To define the clinical, radiologic, and pathologic features of CNS PTLDs.
• To differentiate CNS PTLDs from PTLDs in other organ systems.

Main Methods:

• Retrospective review of 12 primary CNS PTLD cases.
• Analysis of clinical data, neuroimaging findings, and histopathologic features.
• Immunophenotypic and molecular analyses (CD45, CD20, EBV, light chain restriction, immunoglobulin gene rearrangement).

Main Results:

• CNS PTLDs occurred in recipients of various transplants (kidney, liver, heart, stem cells) under immunosuppression.
• Symptoms developed months post-transplant; neuroimaging revealed multiple intra-axial contrast-enhancing lesions.
• Histopathology showed large, malignant lymphoid cells in expanded perivascular spaces, uniformly classified as high-grade, monomorphic PTLDs.
• EBV positivity was common, and light chain restriction/gene rearrangement confirmed clonality.

Conclusions:

• CNS PTLDs are uniformly high-grade lymphomas, distinct from PTLDs in other locations.
• These lymphomas exhibit specific radiologic and pathologic features.
• Prognosis is poor, particularly following peripheral blood stem cell transplantation, though some patients survive over two years.