Myeloma is a type of blood cancer that occurs when abnormal plasma cells of the bone marrow multiply in an uncontrolled way. This differs from leukaemia, which is a cancer of the white blood cells in blood.
Plasma cells develop in the bone marrow (the spongy part in the middle of bone) from B lymphocytes, a type of white blood cell. Plasma cells make antibodies that help the body fight infection.
Myeloma occurs when plasma cells grow abnormally and become myeloma cells. Myeloma cells can:
- produce an abnormal antibody (called monoclonal protein, M-protein or paraprotein) that weakens the immune system and damages the kidneys
- crowd the bone marrow, preventing it from making healthy blood cells
build up in the bone marrow and form tumours in one or many bones of the body; these tumours secrete chemicals that cause other bone marrow cells (called osteoclasts) to remove calcium from bone.