Clinicopathologic Analysis of 34 Japanese Patients With EBV-Associated Reactive Lymphoid Hyperplasias

Area of Science:

• Hematopathology
• Immunology
• Oncology

Background:

• The 5th edition of the WHO classification recognizes hyperplasias in immune deficiency and dysregulation (IDD), often linked to Epstein-Barr virus (EBV).
• EBV-associated reactive lymphoid hyperplasia (EBV-RLH) occurs in diverse IDD contexts, but detailed clinicopathologic data are scarce.

Purpose of the Study:

• To conduct a comprehensive clinicopathologic analysis of EBV-RLH in Japanese patients.
• To characterize the IDD settings, histological patterns, EBV distribution, and clinical outcomes of EBV-RLH.

Main Methods:

• Retrospective analysis of 34 Japanese patients diagnosed with EBV-RLH.
• Review of histological findings, including follicular hyperplasia (FH), infectious mononucleosis-like hyperplasia (IMH), and plasmacytic hyperplasia.
• In situ hybridization for EBER (EBV-encoded RNA), immunohistochemistry for CD79a and CD3, and PCR for IGH/TCRG rearrangements.

Main Results:

• IDD settings included autoimmune diseases, chemotherapy, aging, stem cell transplantation, and HIV infection.
• Histological patterns comprised FH (20 cases), IMH (6 cases), and nonspecific patterns (8 cases).
• EBER-positive cells were predominantly in interfollicular areas and germinal centers (79%). Clonal rearrangements were detected in 3 of 24 cases.

Conclusions:

• EBV-RLH generally follows an indolent clinical course without transformation or mortality.
• Concurrent hematologic malignancies or immune dysregulation post-chemotherapy can be associated with EBV-RLH.
• Thorough histopathologic assessment is vital to differentiate EBV-RLH from concurrent malignancies and guide appropriate management.