Inclusion Criteria:  Patient with WM Patients that may require a first-line or subsequent-line therapy patients who will require treatment initiation patients with serum monoclonal component concentration greater than 15 g/L and who will underwent hyperviscosity assessment, even if hyperviscosity is not found and in the absence of other treatment criteria, no treatment is finally initiated. Patients agreeing to give informed consent.  Exclusion Criteria:  Patients with another chronic B-cell malignancy patients with lymphoplasmacytic proliferations patients with marginal zone lymphoma. patients with WM and histologic transformation Absence of informed consent.