Efficacy of First Line B-RI for Treatment Naive Waldenström's Macroglobulinemia

Inclusion Criteria * Clinicopathological diagnosis of WM as defined by consensus panel one of the Second International Workshop on WM, diagnosed by a reference pathology center. Pathological diagnosis has to occur before study inclusion. In addition, pathological specimens have to be sent to the national pathological reference center at study inclusion. The positivity for Cluster of Differentiation (CD) 20 can be assumed from any previous bone marrow immunohistochemistry or flow cytometry analysis performed up to 6 months prior to enrollment. Inclusion in the study will be based on morphological and immunological criteria. Immunophenotyping will be performed in each center and saved locally. Flow cytometry of bone marrow and blood cells will include at least one double staining and assess the expression of the following antigens: surface immunoglobulin, CD19, CD20, CD5, CD10 and CD23. Patients are eligible if tumor cells express the following antigens: CD19, CD20, and if they are negative for CD5, CD10 and CD23 expression. Patients with tumor cells positive for CD5 and/or CD23 and morphologically similar to WM cells may be included after ruling out other low-grade B-cell malignancies. * Presence of at least one criterion for initiation of therapy, according to the 2nd Workshop on WM: * Recurrent fever, night sweats, weight loss, fatigue (at least one of them) * Hyperviscosity * Lymphadenopathy which is either symptomatic or bulky (≥5 cm in maximum diameter) * Sympto…