The devolution of a mature plasma cell dyscrasia into a fatal plasmablastic lymphoma

Abstract

Introduction: Plasmablastic lymphoma is a rare, aggressive, non-Hodgkin’s lymphoma with an untreated prognosis as poor as three months. There exists scant literature describing transformation of plasmablastic lymphoma from a more benign dyscrasia, the mature plasmacytoma. This case report describes the transformation of plasmablastic lymphoma from a mature plasma cell neoplasm/plasma cell myeloma in an atypical combination of patient characteristics. Case Report: A 66-year-old man presented with acute onset right lower extremity pain and rapidly progressive mobility loss. He was found to have a lytic lesion in the lateral right iliac wing. Biopsy revealed the lesion to be plasmablastic lymphoma with Epstein–Barr virus (EBV) positivity by in situ hybridization with a Ki-67 proliferation index >99%, and strongly staining CD138 and MUM-1. CD20 and PAX-5 were negative. A bone marrow biopsy from the right iliac crest showed mature plasma cells without evidence of plasmablastic lymphoma cytology found in the initial specimen. These specimens showed CD138 positivity with 15–20% plasma cells with Kappa positive clonality by in situ hybridization, and diffusely Epstein–Barr virus negative by in situ hybridization. Further plasma cell fluorescence in situ hybridization study showed a clone with a TP53 deletion and an immunoglobulin heavy chain gene rearrangement that did not translocate to one of the common plasma cell dyscrasia translocation partners (FGFR3, CCND1, MAF, or MAFB). Additionally, a near-tetraploid subclone was observed in approximately 60% of nuclei. Also, there was gain of BCL2 gene or chromosome 18/18q, gain of BCL6 gene or chromosome 3/3q and MYC amplification. There was no MYC and BCL2 and/or BCL6 rearrangements. Our patient was neither HIV-positive nor immunocompromised, rather Epstein–Barr virus positive with a quantitative polymerase chain reaction level greater than 67,000. He was started on Daratumumab combined with etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone. Conclusion: This case exhibits a unique presentation of plasmablastic lymphoma in terms of disease presentation, unique risk factors, including HIV-negativity and male-assigned sex, and the creativity of treatment utilized.