Epstein–Barr virus (EBV)

Epstein–Barr virus (EBV) is a ubiquitous herpes virus that infects almost all human beings worldwide. EBV-related disorders are common and can be either benign or malignant. Infectious mononucleosis is the classic EBV-infected disorder involving lymph nodes and extranodal lymphoid tissues. EBV is the first virus linked with malignancies, both epithelial (nasopharyngeal carcinoma) and lymphoid. EBV infection can transform B lymphocytes and cause EBV-associated lymphomas, including Hodgkin lymphoma, T- and B-cell non-Hodgkin lymphoma as well. Classical Hodgkin lymphoma can be EBV positive in approximately 50% of cases. Less frequently, aggressive NK-cell leukemia, systemic EBV positive T-cell lymphoproliferative disorder of childhood, angioimmunoblastic T-cell lymphoma, post-transplant lymphoproliferative disorder, HV-like lymphoma, and peripheral T-cell lymphoma can also show EBV expression. Mature B-cell lymphomas including diffuse large B-cell lymphoma with chronic inflammation, plasmablastic lymphoma, and lymphomatoid granulomatosis, and some cases of Burkitt lymphoma express EBV. Therefore, it should be a routine part of the workup of these disorders. The presence of EBV is best determined by immunohistochemistry for EBV-related proteins such as LMP1, which is a cytoplasmic staining and in situ hybridization testing for Epstein–Barr virus-encoded RNA (EBER). Immunohistochemistry testing can help determine latency patterns of EBV infection.