Khudur, Sinan

Abstract Introduction/Objective Plasmablastic lymphoma (PBL) is a rare type of B-cell lymphoma with poor prognosis. They can arise de novo in immune deficiency/dysregulation, associated with transplant or transformation of low grade lymphoma. PBL has been reported with anti-CD19 chimeric antigen receptor (CAR) T-cell therapy. Methods/Case Report 69-year-old male with CLL/SLL, treated with multiple chemotherapy regimens and was in remission. He developed generalized weaknesses. Radiology showed lymphadenopathy. Pathology was positive for DLBCL without MYC and BCL2 rearrangement. Flow cytometry revealed 1% CD5 and CD23 positive. TP53 is negative and mutated IGHV. The PD-1 was negative, favored de novo DLBCL. PET-CT and biopsy confirmed residual disease. For refractory DLBCL, CAR-T cell therapy was initiated. Patient developed PBL diffusely positive for CD138, MUM1, c-MYC and kappa; negative for CD19, CD20, PAX5, CD10, BCL6 and CD79a. MIB-1 was 90%. EBV and HHV8 were negative. BCMA was >95 %, Teclistamab was initiated. The renal function deteriorated and proceeded with palliative care. Results NA Conclusion The nature of Richter transformation or de novo DLBCL into PBL in the setting of immunomodulation with CAR-T is rare occurrence. Molecular and clonality studies are needed to evaluate the pathways of losing B-cell markers to evade lineage specific therapy.