What Is Waldenström Macroglobulinemia?

This is the first part of our series about the condition based on our patient booklet “Fast Facts for Patients: Waldenström Macroglobulinemia”. This blog post explains what Waldenström macroglobulinemia (WM) is and how it develops.

First, the Facts …

Waldenström macroglobulinemia (shortened to WM) is a rare blood cancer.
WM usually progresses slowly; some people do not show symptoms for several years after diagnosis.
A person who does not have symptoms usually does not need treatment, but active monitoring is essential so that treatment can be started as soon as it is needed.
Although there is no cure for WM, different treatment options can keep the disease under control for many years in a lot of people.
Eventually, the treatments tend to lose their effect. New therapies are being tested in clinical trials across the world, with promising results.

What Is Waldenström Macroglobulinemia?

WM is a type of non-Hodgkin lymphoma known as lymphoplasmacytic lymphoma (LPL). It is a rare blood cancer in which abnormal cells build up in the bone marrow and other places.

WM most commonly affects people over 60 and slightly more men than women.

To understand WM it helps to get to know some of the terms that your doctor may use and to learn a bit about the biology of the disease. Understanding what causes WM and how the disease develops will help you to ask the right questions and make good treatment choices.

Understanding the Condition

To understand WM it helps to know a bit about normal blood cell production and what goes wrong.

Normal Blood Cell Production

The cells involved in WM are a type of white blood cell called B cells. B cells respond to an infection by changing into plasma cells. The plasma cells make antibodies, which help the body to fight the infection.

How Does Waldenström Macroglobulinemia Develop?

WM develops when a genetic change happens in a B cell as it is developing into a plasma cell. The change or mutation causes the cell to multiply in an uncontrolled way. The abnormal cells carrying the mutation are LPL cells.

This abnormal growth of LPL cells in the bone marrow means normal stem cells that make the different types of blood cells are crowded out. This may result in:

fewer red blood cells
fewer white blood cells
fewer platelets

Low levels of healthy blood cells cause symptoms.

Rarely, LPL cells also grow in the lymph nodes and other organs of the body, such as the spleen, intestine or bones. The nodes or organs may become enlarged, resulting in lumps under the skin in areas like the neck, armpit and groin or inside the body. Occasionally, the spleen enlarges enough to cause abdominal discomfort and a feeling of fullness. Sometimes, people may have changes in their bowel habit, which should be investigated. Tell your doctor if you have any unusual or persistent symptoms.

LPL cells are copies (clones) of one cell type (mono). So the antibodies they produce are also of one type, IgM, and are called monoclonal antibodies. IgM monoclonal antibodies (also called IgM paraproteins or M proteins) are found in the bloodstream of nearly all people with WM.