An immunohistochemical analysis of Reed-Sternberg-like cells in posttransplantation lymphoproliferative disorders: the possible pathogenetic relationship to Reed-Sternberg cells in Hodgkin's disease and Reed-Sternberg-like cells in non-Hodgkin's lymphomas and reactive conditions.

The aim of this study was to assess the incidence and immunophenotype of Reed-Sternberg-like (R-S-like) cells in the setting of posttransplantation lymphoproliferative disorders (PTLD). Twenty-eight formalin-fixed, paraffin-embedded cases (17 renal and 11 heart/heart-lung PTLDS) were analyzed for the presence of typical binucleate cells with inclusionlike nucleoli--the Reed-Sternberg phenotype. An immunohistochemical evaluation for the following markers was performed: CD3, CD20, CD79a, CD15, CD30, CD45, EBV-LMP-1, and vimentin. Monoclonality was assessed by staining for light chain restriction. Eleven cases contained R-S-like cells (9 renal and 2 heart/heart-lung PTLD). All 11 cases were positive for CD45 (LCA), EBV-LMP-1, and vimentin. Ten of 11 cases were CD20/CD79a positive, one case being of a null immunophenotype. Nine cases expressed CD30, whereas 0 of 11 were positive for CD15. In nine cases, expression of both kappa and lambda light chains was present; the remaining two cases failed to express either light chain. This study shows that the R-S-like cells encountered in PTLD have an activated B cell immunophenotype, are invariably EBV-LMP-1 positive, are often CD30 positive, and are CD15 negative. This latter immunophenotypic feature separates R-S-like cells from the R-S cells seen in Hodgkin's disease. The strong staining for EBV-LMP-1 in R-S-like cells also indicates a strong association between EBV-LMP and the R-S morphological phenotype in the context of PTLDs.