Waldenström macroglobulinemia

Waldenström macroglobulinaemia, previously also known as lymphoplasmacytic lymphoma, is a type of B-cell lymphoma. It is a rare condition, accounting for only 1% of all lymphoproliferative disorders. 

Recent publications classify Waldenström macroglobulinaemia as ana lymphoplasmacytic lymphomawith any level of an IgM paraprotein ¹⁰.  Therefore the two entities are not synonymous.

Epidemiology

The incidence is 1,500 cases per annum in the United States. The median age of onset is 60-65 years. A minority of cases occur in the late teens.

Clinical presentation

Most patients are asymptomatic at 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, presentation includes the triad of non-specific B-symptoms: fever, night sweats and unintentional weight loss. Another feature is hyperviscosity syndrome.

Pathology

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

Treatment and prognosis

The International Prognostic Scoring System for Waldenström's macroglobulinaemia is a predictive model for characterisation of long-term outcome. Factors predicting survival are:

• age >65 years
• haemoglobin ≤11.5 g/dL
• platelet count ≤100×109/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.

Complications

• Bing-Neel syndrome: malignant lymphocyte infiltration into the central nervous system (CNS) ¹¹

History and etymology

This condition was first described in 1944 by Swedish haem-oncologist Jan G (Gosta) Waldenström (1906-1996) ^12,13.