Lymphoproliferative diseases in immunocompromised hosts: the role of Epstein-Barr virus.

Epstein-Barr virus (EBV) is a ubiquitous transforming virus of the herpes group showing tropism for B lymphocytes. Primary infection in normal hosts results in a transient lymphoproliferative disorder, acute infectious mononucleosis (IM), that is restricted by cytotoxic and suppressive lymphocytes. However, in the immunodeficient host, EBV-induced lymphoproliferation may behave in a biologically malignant fashion. Patients with primary immunodeficiencies and those with immune incompetence resulting from suppressive therapy in allograft transplantation or infection with human immunodeficiency virus (HIV) have EBV-related illness ranging from fulminant mononucleosis and invasive polyclonal B cell hyperplasia to monoclonal B cell malignancies. While the direct link between EBV and malignant B cell proliferation in these patients has not been elucidated, the association has been increasingly recognized with improved techniques of viral detection. Clinical management can be guided by the location and extent of tumor, histologic features, and clonality. Regional and node-based polyclonal proliferations may respond to prompt reduction of immunosuppressive therapy and efforts to interrupt the replicative cycle with antiviral agents. Systemic cytotoxic therapy often leads to further immunosuppression and should be reserved for patients with progressive disease, advanced visceral involvement, and monoclonal lymphoid malignancies.