ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Multiple Myeloma. To see other pages, use the menu. Think of that menu as a roadmap to this full guide.
Myeloma is a blood cancer of cells found in the bone marrow, specifically the so-called “plasma cells.” The bone marrow is the spongy tissue inside your bones that normally generates the components of your blood. Myeloma begins when healthy plasma cells change and grow out of control. Plasma cells are normally a key part of the body's immune system. In particular, they produce antibodies that help the body fight infection. Abnormal plasma cells can crowd out or suppress the growth of other cells in the bone marrow that produce red blood cells, white blood cells, and platelets. They also reduce the creation of normal plasma cells, which lowers a person’s immunity. This suppression may result in:
Anemia, from a shortage of red blood cells
Excessive bleeding from cuts, from a shortage of platelets
Decreased ability to fight infection, from a shortage of white blood cells and the body’s inability to respond to infection because of the presence of abnormal antibodies
To help you understand this better, it is important to explain that like regular plasma cells, myeloma cells can produce antibodies. However, myeloma cells are unable to produce healthy, functioning antibodies. Instead, they make what is called “monoclonal protein,” or “M protein.” M protein can build up in the blood and urine, potentially damaging the kidneys and other organs, as well as reducing immunity. A healthy person who is found to have a small amount of this M protein is said to have monoclonal gammopathy of undetermined significance (MGUS).
Myeloma causes structural bone damage, which can result in weakened bones and leads to painful fractures or bone breaks over time. Myeloma is usually called multiple myeloma because most people (90% or more) have multiple bone lesions when diagnosed or lesions develop over the course of the illness.
Solitary plasmacytoma is a mass of myeloma cells that involves only 1 site in the bone or, less commonly, other organs, such as in the upper respiratory tract, including the nose and throat or gastrointestinal systems.
Extramedullary plasmacytoma describes myeloma that started outside the bone marrow in locations such as the lymph glands, sinuses, throat, liver, digestive tract, or under the skin.
Normal Bone Marrow
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Multiple Myeloma Disease
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These images used with permission by the College of American Pathologists.
Looking for More of an Introduction?
If you would like more of an introduction, explore these related items. Please note that these links will take you to other sections on Cancer.Net:
ASCO Answers Fact Sheet: Read a 1-page fact sheet  that offers an introduction to this type of cancer. This fact sheet is available as a PDF, so it is easy to print out.
Cancer.Net Patient Education Video: View a short video  led by an ASCO expert in this type of cancer that provides basic information and areas of research.
The next section in this guide is Statistics . It helps explain how many people are diagnosed with this disease and general survival rates. Or, use the menu to choose another section to continue reading this guide.