A case of a diffuse large B-cell lymphoma of plasmablastic type associated with the t(2;5)(p23;q35) chromosome translocation

Anaplastic large cell lymphomas are associated with the t(2;5)(p23;q35) chromosome translocation in 40% to 60% of cases, leading to a new chimeric gene NPM-ALK. NPM-ALK positive lymphomas are generally reported to be of either T cell or null phenotype. In this report, we describe a diffuse large B-cell lymphoma associated with the classic t(2;5) translocation and both nuclear and cytoplasmic expression of ALK. The tumor consisted of medium-sized to large immunoblasts and plasmablasts that on immunohistology were negative for CD30, CD20, and CD79a but showed monotypic cytoplasmic expression of lambda light chains. Clonality analysis confirmed B-cell lineage of the tumor cells. The t(2;5)(p23;q35) chromosome translocation was demonstrated as part of a complex karyotypic alteration by classic banding and spectral karyotyping (SKY) analyses. Reverse transcription polymerase chain reaction confirmed rearrangement of NPM and ALK genes. This case exemplifies that the t(2;5) can, albeit rarely, occur in large B-cell lymphomas and is not entirely limited to anaplastic large cell lymphomas of T or null cell phenotypes.