[Lymphoma genesis in the context of HIV infection].

The incidence of lymphomas is high among HIV infected patients. These lymphomas are non-Hodgkin's lymphoma (NHL) in 70% of cases and Hodgkin's disease (HD) in 30% of cases. Their localization is often extra-nodal with early dissemination. B-cell high grade NHL predominates. The most frequent histological types are diffuse large B-cell lymphoma (30 to 40%) and Burkitt's lymphoma (40 to 50%). Other histological types are low-grade B-cell lymphoma, polymorphic B cell lymphoma and primary effusion lymphoma. Three main factors are predominant in HIV-related lymphomagenesis: cellular immunodeficiency, oncogene viruses (Epstein-Barr and HHV8) and molecular lesions. HIV-related cellular immunodeficiency leads to the increase of EBV infected B-cells and to the diminution of antitumor immunity. Clonal EBV genome is found in lymphoma cells in 30 to 70% of cases of HIV-related NHL. It expresses oncogenic proteins including LMP-1 which behaves like an activated CD40. It induces the expression of intra-cellular genes which stimulate cell growth and inhibit apoptosis. Cytogenetic and molecular lesions are not specific to HIV-related NHL or to histological subtypes. A better knowledge of these mechanisms should lead to the development of specific targeted treatments (antiviral, cytotoxic anti-EBV lymphocytes, cell cycle regulators).