Myeloma is part of a spectrum of diseases characterized by the presence of a paraprotein in the serum that can be demonstrated as a monoclonal, dark-staining band on protein electrophoresis. The paraprotein is produced by abnormal, proliferating plasma cells that produce, most often, IgG or IgA and rarely IgD. The paraproteinaemia may be associated with excretion of light chains in the urine, which are either K or A; the excess light chains have for many years been known as Bence-lones protein.
Myeloma is a disease of the elderly, the median age at presentation being 60 years. It is a complex illness which represents the interrelationship between:
BONE DESTRUCTION causing fractures, vertebral collapse (which can cause spinal cord compression) and hypercalcaemia.
BONE MARROW INFILTRATION resulting in anaemia, neutropenia and thrombocytopenia, together with production of an abnormal protein which may (rarely) result in symptoms of hyperviscosity.
RENAL IMPAIRMENT due to a complex combination of factors, i.e. deposition of light chains, hypercalcaemia, hyperuricaemia and, usually in patients who have had the disease for some time, deposition of amyloid. All of this is further complicated by a reduction in the normal immunoglobulin levels contributing to the tendency for patients with myeloma to have recurrent infections.
Severe anaemia and renal failure at presentation used to be the two main factors associated with a very poor prognosis, with 50% of patients dying within 9 months. The availability of renal dialysis has reduced the impact of renal failure. In patients without these features at presentation, the median survival with treatment is of the order of 2 years.
• Bone pain, most commonly backache due to vertebral involvement
• Symptoms of anaemia
• Recurrent infections
• Symptoms of renal failure
• Symptoms of hypercalcaemia
• Rarely, symptoms of hyperviscosity and bleeding due to thrombocytopenia
FULL BLOOD COUNT:
Hb normal or low
WCC normal or low
Platelets normal or low
ESR almost always high
BLOOD FILM – there may be rouleaux formation as a consequence of the paraprotein
UREA AND ELECTROLYTES – there may be evidence of renal failure
SERUM CALCIUM – normal or raised
SERUM ALKALINE PHOSPHATASE – usually normal
TOTAL PROTEIN – normal or raised
SERUM ALBUMIN – normal or low
PROTEIN ELECTROPHORESIS characteristically shows a monoclonal band
URIC ACID – normal or raised
SKELETAL SURVEY – characteristic lytic lesions, most easily seen in the skull
URINE – for assessment of light chain excretion
BONE MARROW ASPIRATE – shows characteristic infiltration by plasma cells
Bone pain can be helped by radiotherapy. Pathological fractures may be prevented by prompt orthopaedic surgery with pinning of lytic bone lesions seen on the skeletal survey. Renal impairment requires urgent attention and patients may need to be considered for long-term peritoaeal dialysis or haemodialysis. Renal impairment is often a consequence of hypercalcaemia which requires correction with bisphosphonates (disodium etidronate:
i.v. infusion 7.5 mg kg:’ for 3 days) or hydration and systemic steroids if bisphosphonates are not available. Anaemia should be corrected and infection treated. Patients with spinal cord compression known to be due to myeloma are treated with dexamethasone, followed by radiotherapy to the lesion delineated by a myelogram. Hyperviscosity is treated by plasmapheresis, together with systemic therapy.
The use of alkylating agents, e.g. melphalan or cyclophosphamide, given in conjunction with prednisolone has increased the survival from 7 months to 2.5 years. Recently, more intensive doxorubicin-containing regimens have been used, and in selected patients high-dose melphalan with allogeneic or autologous BMT or PBPC rescue have been tried. Adjuvant IFN therapy following both standard chemotherapy and very intensive treatment involving allogeneic or autologous BMT is being evaluated.