Multiple myeloma is a cancer of plasma cells . Plasma cells are found in bone marrow , the blood-producing tissue that fills in spaces within bone.
Plasma cells produce antibodies , substances that help the body fight infection.
Usually, plasma cells make up about one to two percent of all cells in bone marrow. The symptoms of multiple myeloma can vary from person to person, but a common symptom is fatigue. When myeloma cells replace oxygen-carrying red blood cells in the bone marrow, anemia can result causing tiredness or fatigue. Another symptom of myeloma is pain in the back, ribs or other bones, which may be caused by the large number of myeloma cells in bone marrow. The pain, which can be severe, may occur months before a diagnosis is made.