HEMOPHAGOCYTIC SYNDROME IN EPSTEIN-BARR VIRUS-ASSOCIATED T-LYMPHOPROLIFERATIVE DISORDERS - DISEASE SPECTRUM, PATHOGENESIS, AND MANAGEMENT

The Epstein-Barr virus (EBV) has been shown to infect T lymphocytes and is associated with two recently recognized human T-lymphoproliferative disorders: childhood EBV-associated hemophagocytic syndrome (VAHS) representing a primary or active EBV infection of T cells in young children, and the EBV-containing T cell lymphoma in adults predominantly affecting the nose, skin and gastrointestinal tract. In both diseases, hemophagocytic syndrome (HS) accounts for the major cause of mortality. The patients developing HS share common clinicopathologic features such as fever, skin lesions, lung infiltrates, hepatosplenomegaly with jaundice, cytopenias, and coagulopathy. The liver, spleen, lymph nodes, and bone marrow usually show florid histiocytic proliferation with hemophagocytosis in addition to the proliferation of atypical T lymphocytes or immunoblasts. The HS in T cell lymphoma may develop simultaneously with initial lymphoma presentation, at tumor relapse, or even during remission. The cytokines, in particular tumor necrosis factor-alpha, released from the EBV-infected T lymphocytes are presumed to cause the histiocytic activation and the subsequent hemophagocytic process. Chemotherapy or antiviral agents fail to arrest the hemophagocytic process in both diseases. Immunomodulatory treatment incorporating etoposide and intravenous immunoglobulin, however, has been effective in the control of the progression of the hemophagocytic process in a substantial number of VAHS patients. Preliminary data suggest that bone marrow transplantation may be a promising way for eliminating both the virus and the proliferating T cells. Further investigations are mandatory for combating this aggressive hemophagocytic process in EBV-associated T lymphoproliferative disorders.