Pyothorax-associated pleural lymphoma. A case evolving from T-cell-rich lymphoid infiltration to overt B-cell lymphoma in association with Epstein-Barr virus.

Background. Pyothorax-associated pleural lymphomas (PAPL) occur in patients with long-standing pyothorax. Epstein-Barr virus (EBV) plays an important role in its development. Methods. An atypical case of PAPL is reported and its clinical features are compared with those of five cases of ordinary PAPL. Results. The histology of the lymphoma changed from prominent T-cell infiltration to an overt B-cell lymphoma of diffuse, large cell-type. DNA studies of the lymphoma at the first presentation demonstrated dual rearrangement in the T-cell receptor beta (TCR beta) and immunoglobulin heavy chain J region (IgJH) genes. EBV genome analysis demonstrated monoclonal expansion of EBV-infected cells. EBV gene products were present only in large lymphocytes with B-cell phenotype. The same rearranged band of the IgJH gene, but not clonal rearrangement of the TCR beta gene, was observed in the overt B-cell lymphoma at the relapse. The same EBV-infected clone was observed throughout the course of the disease. The tumor was localized at the pyothorax wall, and cell-mediated immunity, reflected by a positive tuberculin reaction, was preserved only in the current case. Conclusions. T-cell-rich lymphoid infiltration in the current case is a variant of EBV-associated PAPL, which is infiltrated by reactive T-cells with clonal accentuation. This is the first documented case of EBV-associated PAPL evolving from T-cell-rich lymphoid infiltration.