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What is Waldenstrom’s macroglobulinaemia (WM)?

What is WM

What is WM?

Waldenstrom’s macroglobulinaemia (WM) is a rare type of blood cancer. It develops when some of the body’s white blood cells change and grow out of control.

It is sometimes called lymphoplasmacytic lymphoma and is one of the family of cancers of the lymphatic system known as Non-Hodgkins lymphoma (NHL). Doctors may use any of these terms when discussing your WM with you.

It is a slow-growing cancer with its own distinct characteristics that require specialised treatment and care.

Jan Waldenström was the Swedish doctor who first described the disease in 1944 and lent it his name; “macroglobulinaemia” refers to the high levels of immunoglobulin M (IgM) seen in the blood stream of 95% of WM patients. IgM is natural, it is produced by B cells in the bone marrow to fight infection. However, in WM, defective ‘B’ cells produce large quantities of non-functional IgM paraproteins which are not useful to the body and can cause damage.

Who is affected by WM?

  • Around 400 people are diagnosed with WM each year in the UK
  • It is estimated that 4000 people are currently living with WM in the UK
  • Traditionally viewed as a disease that affects people over the age of 65, it is now increasingly seen in younger age groups
  • It is more common in men than women
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What causes WM?

The cause of WM is still unknown. It is not infectious and cannot be passed onto other people.

In most cases, WM is preceded by a condition known as MGUS (monoclonal gammopathy of uncertain significance), and experts think this is how WM starts. This is where there is an abnormal amount of IgM detectable but people have no other symptoms and usually feel well. It may be picked up in a blood test for another unrelated condition. For most people, this has no long-term implications and they are monitored over time for any rise in IgM which may indicate WM.

WM can occur within families. Research has found that almost 1 in 5 people with WM have a relative with WM or a related blood cancer. This suggests that there may be a genetic tendency for developing WM but it does not appear to be directly inherited down the family line. Genetic screening of family members is not currently offered as the risk is still very small.

Research in the USA has found that most people with WM (90%+) have a genetic mutation called MYD88. Genetic screening at diagnosis is becoming more common in the UK including for a second WM mutation called CXXR4. These mutations may impact how people respond to new novel treatments at a molecular level.

Symptoms of WM

WM often develops over a long period of time (years), and some people have no symptoms at all. However, most people will gradually develop symptoms of WM for two main reasons:

  1. The abnormal cells are filling up the bone marrow or collecting in the lymph nodes or spleen.
  2. Large amounts of IgM are circulating in the bloodstream or targeting tissue and nerves.

Symptoms include:

  • tiredness, weakness and breathlessness
  • infections
  • bruising or bleeding easily
  • swollen glands
  • fevers and night sweats
  • weight loss
  • blurring or loss of vision
  • dizziness or headaches
  • drowsiness, poor concentration or confusion
  • lumps or masses (rare)
  • central nervous system problems such as fits, weakness of facial muscles, double vision (very rare)

You may hear these terms in relation to WM symptoms:

Hyperviscosity

This is when your blood becomes thicker and more slow-flowing than normal due to large amounts of IgM in your bloodstream.  It affects up to 30% of people with WM. Hyperviscosity can cause changes in the back of the eyes, due to pressure in the retinal blood vessels, as well as shortness of breath, nosebleeds, blurred vision and dizziness.

Peripheral Neuropathy

Sometimes, the large amounts of IgM in your bloodstream can damage the nerves in the body’s extremities, causing numbness or tingling in hands and feet, or problems with balance.

Cold Agglutinin Disease (CAD)

In some people with WM, the IgM can cause the red blood cells to stick together in the coolest parts of the body, such as hands and feet, tip of the nose or the ear lobes. This can cause poor circulation in these areas. Some people experience a condition called cold agglutinin disease, where the clumps of red blood cells in the extremities are broken down by the immune system, which needs prompt treatment including a blood transfusion.

It is important to mention all your symptoms to the doctor, especially if symptoms are changing or getting worse over time.

Diagnosis

WM is sometimes found by chance while having investigations for another condition or a routine blood test. A quarter of people with WM are diagnosed in this way.

Three-quarters of people with WM will be diagnosed following a series of tests that may include:

Blood tests

Various blood tests will be done to identify levels of IgM, red and white blood cells, and platelets. Because IgM is a large molecule, it is often difficult to monitor the amount of protein accurately. You may be told the total IgM level or just the level of the abnormal IgM paraprotein. Both are helpful, but it is important to be consistent during follow up so that you and the doctor can monitor levels effectively.

Bone marrow biopsy

Since WM is a disease of the bone marrow, samples of the bone marrow are needed to confirm whether you have WM and the level of the disease. A bone marrow biopsy involves taking samples from the back of your hip bone (pelvis).

CT (computed tomography) scan

This is a special type of x-ray that is used to find out whether WM has affected your lymph nodes, or organs such as the liver or spleen. A number of pictures are taken from different angles and fed into a computer which shows detailed pictures of the inside of the body.