An unusual case of primary effusion lymphoma in a HIV-negative patient not pathogenetically associated with HHV8

The development of an unusual case of primary pleural effusion in a 90-year-old human immunodeficiency virus (HIV)-negative Japanese woman with no identifiable tumor mass has been described. Pleural effusion specimens contained large diffuse lymphoma cells, with the phenotype and genotype of a B-cell lineage (positive for CD20, CD79a and clonal rearrangement of Ig heavy chain) and the c-myc gene rearrangement, but were negative for T-cell markers (CD45RO and CD3). The patient was negative for human herpes virus 8 (HHV8), Epstein-Barr virus (EBV) and hepatitis C virus (HCV), as well as human T-cell lymphotropic virus type-1 (HTLV-1). The patient died of respiratory failure 5 months after the diagnosis of primary effusion lymphoma (PEL), and an autopsy was performed. Autopsy findings revealed no evidence of tumor mass or bone marrow involvement of lymphoma cells. This case has been considered as a PEL in a HIV-, HHV8-, EBV- and HCV-negative patient. Although cytomorphology of lymphoma cells was classified as large-cell lymphoma in this case, it is interesting that the present case may represent an unusual subset of Burkitt-like disease because of clear B-cell phenotype and c-myc gene rearrangement.