Waldenström's macroglobulinemia (WM) is a B-cell lymphoproliferative disorder which is defined by bone marrow infiltration by small lymphocytes, lymphoplasmacytoid and plasma cells together with the presence of a detectable monoclonal immunoglobulin M (IgM).The clinical presentation of WM is variable. Symptoms can be related to tumor infiltration, or they can be related to the monoclonal IgM component. The therapeutic options are heterogeneous and there are no well-established in both first line or relapse/refractory settings. In Spain, the incidence of MGUS-IgM and WM in the last decade is unknown.

The aims of this retrospective, observational, multicentric study is:

• To develop a national registry of patients diagnosed with Waldenström's Macroglobulinemia and Monoclonal Gammopathy of uncertain significance -IgM in Spain in the past 30years.
• To evaluate the most relevant clinical characteristics, long-term safety and efficacy of different therapeutic schemes and long-term prognosis of patients with WM
• To help in the design of future therapeutic strategies, risk prognostic factors and clinical trials in Spain.

Methods:

The investigators will collect data from the patient clinical files after prior Informed Consent providing from patients with diagnosis of MGUS-IgM and WM in the past 30 years in Spain, according to the WHO classification of lymphoid tumors (2008) revised in 2016. Data from patients not able to provide IC (i.e., already dead patients) will be included only after the permission of the ethics review board.

The collected data will be included in a database of the Spanish Myeloma and Lymphoma Intergroup (SMALI) team created ad-hoc by the Spanish Society of Hematology and Hemotherapy (SEHH). Each principal investigator in each center will conduct their technical supervision. The evaluation of the treatment protocols will be done following the indications of the intergroup committee according to the guidelines of the International Waldenström's Macroglobulinemia Group.

Inclusion Criteria:

• Age ≥18 years
• Patients having a confirmed diagnosis of either in the las 30 years:
• Monoclonal Gammopathy of uncertain significance -IgM
• Asymptomatic Waldenström's macroglobulinemia
• Symptomatic Waldenström's macroglobulinemia

Exclusion Criteria:

• Other subtypes of Lymphoproliferative diseases.

Patients diagnosed with Waldenström's Macroglobulinemia and Monoclonal Gammopathy of uncertain significance