Information and Resources for Patients

About Waldenström Macroglobulinemia (WM)

WM is a rare form of blood cancer.

  • Only about 1,500 patients are diagnosed with WM each year in the US.
  • In Europe, about 2,500 patients develop this disease annually.

WM is usually slow growing, so many people have it for a long time before they begin to develop noticeable symptoms. There are helpful treatments, however, at this time there is no cure.

What happens when a person gets WM?

The disease occurs in a type of white blood cell called B-lymphocytes.

  • Normally, B-lymphocyte cells mature into plasma cells that help the body fight off infections by making antibodies.
  • In WM, the B-cells mature into abnormal cells and continue making bad copies that do not properly fight off infections. These B-cell mutations also over-produce an antibody called IgM.
  • Evidence of these abnormal B-cells can be found in the bone marrow, lymph nodes, and other tissues and other organs like the liver and spleen.
  • Over time, these mutated B-cells and high levels of IgM begin to cause symptoms and interfere with normal functioning.

How is WM diagnosed?

A blood test can provide a panel of important information when diagnosing WM.

Depending on the results of the blood panel, a bone marrow biopsy may also be needed.

The blood test and bone marrow biopsy test to see how many of the B-cells are maturing into mutated copies, and how much of the bone marrow is infiltrated by the cells making bad copies.

What causes WM symptoms to appear?

  • WM may alter a person’s blood count. The bone marrow is where many important cells are made like red blood cells, white blood cells and platelets. In a case of WM, the mutated B-cells may begin to “crowd out” the normal blood cells. If the bone marrow has an overpopulation of mutated B-cells, production of other important cells may begin to falter. The WM cells may cause enlarged lymph nodes and other complications.
  • The over-production of IgM may also cause many of the symptoms associated with the disease. IgM is a large antibody and tends to make the blood thicker than normal, a condition called hyperviscosity. Unlike normal antibodies that fight infection, the IgM produced by WM cells has no useful function. Sometimes the IgM may incorrectly recognize the body’s healthy tissues as “foreign” and attach to them, causing inflammation and injury.

How does WM usually progress in a person?

There Are Two Early Stages:

  • Before a person is diagnosed with WM, they nearly always have what is called a “precursor condition.”
  • The earliest one is often referred to as IgM MGUS for short, which stands for IgM Monoclonal Gammopathy of Undetermined Significance.
  • Following IgM MGUS, a person may progress to a later stage known as Smoldering Waldenström Macroglobulinemia (SWM).

Although neither of these early stages will cause noticeable symptoms, people with SWM have a higher risk of progressing to symptomatic WM, which means they should have closer monitoring by a healthcare provider.

According to previous reports, 1.5% of IgM MGUS cases progress to WM each year and that number increases to 12% for those who have SWM.  Even after a person’s condition has progressed to WM, they may remain free from symptoms which indicates they are still at a lower risk for progression.

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