Multiple Myeloma

Key points

• • Multiple myeloma is a malignant overgrowth of plasma cells in the bone marrow, mostly affecting older adults.
• • The cancerous plasma cells all come from one clone and pour out a single, identical antibody (a monoclonal, or M, protein) into the blood.
• • This shows as a sharp M band on serum protein electrophoresis, and free monoclonal light chains (Bence Jones protein) appear in the urine.
• • The plasma cells crowd the marrow and release factors that dissolve bone, causing bone pain, punched-out holes on X-ray, fractures and a high blood calcium.
• • Other features are anaemia (from marrow crowding), kidney failure (from the light chains) and a tendency to infection (from a lack of normal antibodies).
• • The blood film often shows red cells stacked like coins (rouleaux) because of the high protein level.