What Is It?
Multiple myeloma is cancer of the bone marrow caused by the uncontrolled growth of plasma cells. These cells are one type of white blood cells. Normally, they make antibodies called immunoglobulins to fight infections.
In multiple myeloma, cancerous plasma cells multiply rapidly in the bone marrow and invade the outer layers of the bones. They also make too much of one specific type of immunoglobulin (an antibody protein). Large amounts of immunoglobulins in the bloodstream may cause the blood to become thick and sticky. This can lead to blood clots.