[Transformation of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia into diffuse large B-cell lymphoma: five cases report and literature review].

Objective: To analyze the clinical features and prognosis of patients with lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) transformed into diffuse large B-cell lymphoma (DLBCL) . Methods: This study retrospectively analyzed the clinical data of five patients with LPL/WM transformed to DLBCL diagnosed and treated at a multicenter hospital in Hunan Province from December 2020 to April 2023. Clinical manifestations, treatment regimens, and therapeutic efficacy before and after the transformation were compared. Results: Of the five patients, four were male and one was female, with a median age of 64.0 (57.0-80.0) years, all of whom had abnormally increased β(2)-microglobulin levels at diagnosis, and two were combined with increased lactate dehydrogenase levels. The MYD88(L265P) mutation was detected in 4 patients, whereas 1 carried the FAT1 and NOTCH1 mutations, and none demonstrated CXCR4 mutations. Three patients were negative for the TP53 mutation, and two were not tested. Before transformation, three patients were treated with Bruton tyrosine kinase inhibitor therapy, and one patient was treated with the bendamustine plus rituximab regimen. All patients eventually transformed into non-growth center-derived DLBCL, with a median time to conversion of 11.8 (4.0-19.0) months, and most of them presented with weight loss, lymph node enlargement, splenomegaly, and extranodal involvement. Posttransformation, the patients were mainly treated with the rituximab, cyclophosphamide, hydroxydaunorubicin, oncovin, and prednisone (R-CHOP) regimen, with an optimal outcome of partial remission. Disease progression occurred in 4 of the patients, with a median overall survival of 16.8 (10.0-26.0) months. Conclusion: Transformation from LPL/WM to DLBCL is rare. Patients should remain highly vigilant for transformation if they develop rapidly enlarging lymph nodes and/or newly involved lymph nodes, worsening systemic symptoms, and declining body mass. R-CHOP regimen may induce a partial response in some cases; however, the overall prognosis remains poor.