They interfere with the growth and function of normal plasma cells. Myeloma cells collect in the bone marrow and in the outer hard part of the bones. They can form a large mass called a tumor or plasmacytoma. It is important to remember that this cancer is very different from bone cancer. Multiple myeloma begins in the cells of the immune system and affects the bones.
Bone cancer begins in cells that make up the hard outer part of the bone.
The diagnosis and treatment for multiple myeloma are very different from the diagnosis and treatment for bone cancer. Because people with multiple myeloma have an abnormal number of identical plasma cells, they also have too much of one type of antibody. These myeloma cells and antibodies can cause a number of serious problems. They damage and weaken bones, causing pain and sometimes fractures. The damaged bones release calcium into the blood causing a condition called hypercalcemia.