Herpes virus type 8-negative primary effusion lymphoma associated with PAX-5 gene rearrangement and hepatitis C virus - A case report and review of the literature

At present, there is no case report of HHV8(-) primary effusion lymphoma (P EL) with t(9;14) (p13;q32) involving both PAX-5 and immunoglobulin heavy ch ain gene rearrangement, which is a rare translocation in B-cell non-Hodgkin 's lymphoma, in an HIV- patient. We examined an HIV-seronegative 63-year-ol d Japanese man with hepatitis C virus-associated liver cirrhosis and hepato cellular carcinoma manifesting peritoneal lymphomatous effusion without tum or mass at any body site. The lymphoma cells were examined twice by light m icroscopy, immunohistochemistry, three-color flow cytometry, cytogenetics, and molecular analyses. The nuclear morphology of lymphoma cells was simila r to that of large noncleaved cells, although the lymphoma cell size was a little smaller that of the usual large-cell lymphoma. Immunophenotyping of lymphoma cells in the ascitic fluid revealed a mature peripheral B-cell phe notype (CD5(-) CD10(-) CD19(+) CD20(+) CD22(+) Ig G(+) lambda(+)). Cytogene tics showed a clonal population: 45,X,-Y, der(2) t(2;6)(q31;p21.3), t(4;s)( q21;q11.2), der(6) t(2;6)(q31;p21.3) add(6)(q15), t(9;14)(p13;q32.3) [10]/4 7, idem, +der(6) t(2;6), +16 [10]. Southern blot analysis revealed rearrang ed fragments with a probe for immunoglobulin heavy chain, some of which wer e a size similar to those with a PAX-5 gene probe. Polymorphism, not rearra ngement, of the c-MYC gene, was also found. HHV8 and the Epstein-Barr Virus were not detected by polymerase chain reaction. This case is the first rep ort of an HHV8(-) PEL with t(9;14) involving a PAX-5 gene rearrange ment in an HIV-seronegative patient. This primary effusion lymphoma manifested spo ntaneous regression without any therapy. These findings suggest that there may be an additional subcategory of primary effusion lymphoma that is not a ssociated with HHV8 nor c-MYCR but is pathogenetically associated with the PAX-5 gene or hepatitis C virus.