[1313] Plasmablastic Differentiation in Low Grade B-Cell Lymphomas: An Unusual Histological Transformation.

Daniel Martinez, Luis Colomo, Maria Rozman, Alejandra Valera, Eva Gine, Armando Lopez-Guillermo, Salome Martinez, Krzysztof Warzocha, Tadeusz Robak, Magdalena Czader, Elias Campo, Antonio Martinez. Hospital Clinic, University of Barcelona, Spain; Hospital Universitari Joan XXIII, Tarragona, Spain; Institute of Hematology, Warsaw, Poland; Medical University of Lodz, Poland; University of Indiana, Indianapolis

Background: Histological transformation of low grade B-NHL to DLBCL is a well known event associated with poor prognosis. Although plasma cell differentiation may occur in low grade B-NHL, an overt plasmablastic transformation (PBL-T) has been only rarely reported. Plasmablastic lymphoma (PBL) is a very aggressive disease with mainly extranodal presentation in association with immunodeficiency. Whether the PBL-T of low grade B-NHL may mimic clinically, histologically and biologically plasmablastic lymphomas has not been addressed.
Design: A secondary PBL-T was identified in five cases of low grade lymphoid neoplasms. Histology, immunophenotype, cytogenetics, clonal relationship as well as clinical data were reviewed.
Results: A PBL-T was identified in two follicular lymphomas (FL) and three chronic lymphocytic leukemias (CLL/SLL). The patients were 4 males and one female 57 to 70 year old. In three cases, the PBL-T was identified simultaneously with the low grade component in the two FL and in one CLL/SLL. In two CLL/SLL, the PBL-T occurred 47-85 months after the initial diagnosis. Four patients received chemotherapy after transformation (R-CHOP in three cases and VAD/CHOP in one) and one received palliative radiotherapy. Four patients died 3-24 months after transformation. None of them had prior history of immunodeficiency. In three cases the PBL-T occurred in an extranodal site. Only two patients received prior chemotherapy one for CLL/SLL and one for incidental seminoma. All PBL-T had predominant immunoblastic histology with admixed plasma cells and a plasmablastic phenotype being CD20 negative, CD138 positive (4/4) and lambda light chain expression. All cases were negative for EBV and HHV8. Among FL transformed cases, both components harbored the t(14;18) and were clonally related. One ZAP70 positive CLL/SLL presented at diagnosis with a clonally related PBL-T whereas in the other cases the PBL-T was clonally unrelated to the initial CLL/SLL. Only one FL had a MYC translocation in the transformed component.
Conclusions: PBL-T of low grade B-NHL is morphological and phenotypically similar to primary PBL but is not associated with an apparent immunodeficiency, EBV infection or the MYC translocation present in PBL. This is a rare and aggressive transformation of low grade B-NHL previously misrecognized.
Category: Hematopathology

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 186, Monday Morning


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