Plasmablastic transformation of low-grade CD5+ B-cell lymphoproliferative disorder with MYC gene rearrangements.

Plasmablastic transformation of low-grade B-cell lymphoproliferative disorders is rarely reported, particularly in cases with clonal evolution. Moreover, the relationship of these 2 morphologically and immunophenotypically distinctive neoplasms remains elusive. Here, we report 2 exceptional cases of plasmablastic transformation with apparently direct transformation from their preceding low-grade B-cell lymphoproliferative disorder. In both cases, the plasmablastic transformation and low-grade lymphoproliferative disorder shared the same immunoglobulin heavy chain gene rearrangements and an identical chromosomal translocation. Notably, both plasmablastic transformation cases also carried MYC gene rearrangements on chromosome 8q24, which have been frequently identified in de novo plasmablastic lymphoma. Therefore, our data suggest that dysregulation of MYC gene may play a critical role in the pathogenesis of plasmablastic transformation.