Single Centre Retrospective Analysis: Transformation of Waldenström's Macroglobulinemia to Diffuse Large B-Cell Lymphoma

Introduction: The incidence and outcome of Waldenström's macroglobulinemia (WM) patients with transformation to diffuse large B-cell lymphoma (DLBCL) are unclear. We performed a retrospective analysis to determine the incidence, clinicopathological characteristics and treatment outcome of WM patient with histologic transformation to DLBCL in our centre.

Methods: Single centre chart review of WM patients in the past 10 years. Patients with histologic diagnosis of DLBCL after the diagnosis WM were included in our analysis.

Results: Three of the 79 WM patients had histological transformation to DLBCL, two male and one female. Mean age at DLBCL development was 76,6 years. The mean time to transformation since diagnosis of WM was 8,3 years (14, 8 and 3 years). All three patients received at least one prior line of treatment in relation to WM (2, 1 and 3 prior lines). Different regimens used were cyclophosphamide/dexamethasone, rituximab/bendamustin, chlorambucil monotherapy, fludarabine monotherapy, R-CVP and ibrutinib monotherapy. The patients were in clinical CR from WM at the time of transformation, two patients were still on treatment.

All three patients presented with advanced disease (stage IIIB, IVB, and IVA) non-GCB subtype DLBCL with at least 2 extra nodal sites. R-IPI scores were 4,5 and 4.

Two patients were treated with R-miniCHOP, one patient received R-CHOP. The first patient achieved a CR at the end of treatment and is now 1,5 years in follow-up. The second patient died from pneumonia one year after achieving a CR. The third patient is in follow op since 3 months after reaching a CR at the end of treatment.

Conclusion:

1. Over the past decade transformation of WM to DLBCL was 3.7% in our centre. This is in accordance with previous data suggesting an 2.4% risk of transformation over 10 years.

2. Time to transformation varies and no association with prior WM therapy and response to treatment can be found.

3. All patients presented with more aggressive DLBCL in an advanced stage.

4. All three patients achieved a CR following treatment for DLBCL, one patient died from pneumonia, two others are now in follow-up 1,5 years and 3 months respectively.