PRIMARY EFFUSION LYMPHOMA - A DISTINCT CLINICOPATHOLOGICAL ENTITY ASSOCIATED WITH THE KAPOSIS SARCOMA-ASSOCIATED HERPES-VIRUS

We recently discovered the Kaposi's sarcoma-associated herpes virus (K SHV/HHV-8) in an uncommon and unusual subset of AIDS-related lymphomas that grow mainly in the body cavities as lymphomatous effusions witho ut an identifiable contiguous tumor mass. The consistent presence of K SHV and certain other distinctive features of these body cavity-based lymphomas suggest that they represent a distinct entity. We tested thi s hypothesis by investigating 19 malignant lymphomatous effusions occu rring in the absence of a contiguous tumor mass for their clinical, mo rphologic, immunophenotypic, viral, and molecular characteristics. KSH V was present in 15 of 19 lymphomas. All four KSHV-negative lymphomato us effusions exhibited Burkitt or Burkitt-like morphology and c-myc ge ne rearrangements and, therefore, appeared to be Burkitt-type lymphoma s occurring in the body cavities. In contrast, all 15 KSHV-positive ly mphomatous effusions exhibited a distinctive morphology bridging large -cell immunoblastic lymphoma and anaplastic large-cell lymphoma, and a ll 12 cases studied lacked c-myc gene rearrangements. In addition, the se lymphomas occurred in men (15/15), frequently but not exclusively i n association with HIV infection (13/15), in which homosexuality was a risk factor (13/13), presented initially as a lymphomatous effusion ( 14/15), remained localized to the body cavity of origin (13/15), expre ssed CD45 (15/15) and one or more activation-associated antigens (9/10 ) in the frequent absence of B-cell-associated antigens (11/15), exhib ited clonal immunoglobulin gene rearrangements (13/13), contained Epst ein-Barr virus (14/15), and lacked bcl-2, bcl-6, ras and p53 gene alte rations (13/15). These findings strongly suggest that the KSHV-positiv e malignant lymphomatous effusions represent a distinct clinicopatholo gic and biologic entity and should be distinguished from other maligna nt lymphomas occurring in the body cavities. Therefore, we recommend t hat these malignant lymphomas be designated primary effusion lymphomas (PEL), rather than body cavity-based lymphomas, since this term descr ibes them more accurately and avoids their confusion with other malign ant lymphomas that occur in the body cavities. We further recommend th at these PEL be considered for inclusion as a new entity in the Revise d European-American Lymphoma Classification. (C) 1996 by The American Society of Hematology.