Pathologically, AIDS-related lymphomas are comprised of a narrow spectrum of histologic types consisting almost exclusively of B-cell tumors of aggressive type. These include:

• Diffuse large B-cell lymphoma.
• B-cell immunoblastic lymphoma.
• Small noncleaved lymphoma, either Burkitt or Burkitt-like.

All three pathologic types are equally distributed and represent aggressive disease.

AIDS-related lymphomas, though usually of B-cell origin as demonstrated by immunoglobulin heavy-chain gene rearrangement studies, have also been shown to be oligoclonal and polyclonal as well as monoclonal in origin. Although HIV does not appear to have a direct etiologic role, HIV infection does lead to an altered immunologic milieu. HIV generally infects T lymphocytes whose loss of regulation function leads to hypergammaglobulinemia and polyclonal B-cell hyperplasia. B cells are not the targets of HIV infection. Instead, Epstein-Barr virus (EBV) is thought to be at least a cofactor in the etiology of some of these lymphomas. The EBV genome has been detected in varying numbers of patients with AIDS-related lymphomas; molecular analysis suggests that the cells were infected before clonal proliferation began.[1] EBV is detected in 30% of patients with small, noncleaved lymphomas and in 80% of patients with diffuse, large cell lymphomas. The rare, primary effusion lymphoma consistently harbors human herpes virus type-8 and frequently contains EBV.[2] HIV-related T-cell lymphomas have also been identified and appear to be associated with EBV infection.[3]

References

1. Thorley-Lawson DA, Gross A: Persistence of the Epstein-Barr virus and the origins of associated lymphomas. N Engl J Med 350 (13): 1328-37, 2004.  [PUBMED Abstract]
   
   
2. Simonelli C, Spina M, Cinelli R, et al.: Clinical features and outcome of primary effusion lymphoma in HIV-infected patients: a single-institution study. J Clin Oncol 21 (21): 3948-54, 2003.  [PUBMED Abstract]
   
   
3. Thomas JA, Cotter F, Hanby AM, et al.: Epstein-Barr virus-related oral T-cell lymphoma associated with human immunodeficiency virus immunosuppression. Blood 81 (12): 3350-6, 1993.  [PUBMED Abstract]