Waldenström macroglobulinemia

Last revised by Joshua Yap on 20 Jan 2023

Waldenström macroglobulinemia is a subtype of lymphoplasmacytic lymphoma (LPL), a form of B-cell lymphoma.

Recent publications classify Waldenström macroglobulinemia as a subtype of lymphoplasmacytic lymphoma with any level of an IgM paraprotein; these two conditions are not synonymous 10.

It is a rare condition, accounting for only 1% of all lymphoproliferative disorders. The incidence is 1500 cases per year in the United States. The median age of onset is 60-65 years. A minority of cases occur in late adolescence.

Most patients are asymptomatic at the time of diagnosis, which is often incidentally made during blood tests for an unrelated condition. If symptoms occur, the most common ones are fatigue (2/3 of cases) and polyneuropathy (1/4 of cases). Otherwise, the presentation includes the triad of non-specific B-symptoms: fever, night sweats, and unintentional weight loss. Another feature is hyperviscosity syndrome.

Another recognized presentation is Schnitzler syndrome: where Waldenström macroglobulinemia manifests as an urticarial skin vasculitis.

The pathogenesis is poorly understood but may resemble that of chronic lymphocytic leukemia. Clonal proliferation of functionally impaired B-cells occurs, as well as infiltration of various tissues (predominantly bone marrow, spleen, and lymph nodes). There is an overproduction of IgM, leading to hyperviscosity syndrome and resultant impaired microcirculation.

There have been relatively few articles on the imaging features of Waldenström macroglobulinemia. Authorities do not recommend imaging as part of the initial workup of patients 14.

Bone marrow involvement is the most common imaging manifestation, best appreciated on MRI. One study found that MRI spines were abnormal in 91% of cases with two main appearances seen 14:

  • diffuse: all bone marrow signal is abnormal

  • heterogeneous: myriad small foci of abnormal signal scattered throughout uninvolved bone marrow

The International Prognostic Scoring System for Waldenström macroglobulinemia is a predictive model for characterization of long-term outcome. Factors predicting survival are:

  • age >65 years

  • hemoglobin ≤11.5 g/dL

  • platelet count ≤100 x 109/L

  • B2-microglobulin >3 mg/L

  • serum monoclonal protein concentration >70 g/L

Risk categories are:

  • low: ≤1 adverse variable except age

  • intermediate: 2 adverse characteristics or age >65 years

  • high: >2 adverse characteristics

Five-year survival rates for these categories are 87%, 68%, and 36% respectively.

Untreated, the disease typically progresses indolently, and behaves differently among patients.

This condition was first described in 1944 by Swedish heme-oncologist Jan Gosta Waldenström (1906-1996) 1,12.

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