B-cell lymphoid tumors that occur in association with AIDS. patients often present with an advanced stage of disease and highly malignant subtypes including burkitt lymphoma; IMMUNOBLASTIC LARGE-CELL LYMPHOMA; PRIMARY EFFUSION LYMPHOMA; and DIFFUSE, LARGE B-CELL, LYMPHOMA. The tumors are often disseminated in unusual extranodal sites and chromosomal abnormalities are frequently present. It is likely that polyclonal B-cell lymphoproliferation in AIDS is a complex result of EBV infection, hiv antigenic stimulation, and T-cell-dependent hiv activation.