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. This can weaken bones so much that minimal trauma can cause a bone fracture at the cancer site.