This malignant tumour of plasma cells is more common than the primary tumours of bone, and causes widespread osteolytic lesions in any bone, particularly the vertebrae, pelvis, ribs, and skull. When extraosseous lesions occur, they are usually formed by tumour growing from a bone.
The patient, who is equally likely to be a man or a woman, and is usually between 40 and 70, presents with bone pain, especially in his back (75%), anaemia (50%), ill health, and loss of weight. He may also have anaemia, renal impairment, hypercalcaemia, and decreased resistance to infection. In practice, the diagnosis is difficult, because of the non-specific nature of his presenting symptoms.
MYELOMA X-RAYS may show well defined osteolytic lesions, usually without cortical thickening or sclerosis, but sclerotic lesions can occur, especially after treatment. Sometimes, there are no discrete bony lesions.
SPECIAL TESTS. (1) Bence Jones protein is present in the urine of 50% of cases (this precipitates during heating, and dissolves again near boiling point). (2) Increased immunoglobulins in the blood (95%). (3) The alkaline phosphatase is nearly always normal, the prothrombin index is increased, and the ESR greatly so. (4) Bone marrow biopsy confirms the diagnosis, and shows many abnormally large plasma cells, with poorly defined chromatin. Take a core specimen in addition to aspirating it, because tumour cells are usually in foci.
THE DIFFERENTIAL DIAGNOSIS includes senile osteoporosis (especially when this produces kyphosis), carcinomatosis of bone and myelofibrosis.
THE COMPLICATIONS include: infections, especially of a patient's chest and urinary tract; anaemia; renal impairment due to Bence Jones protein and hypercalcaemia; pathological fractures (uncommon early but common late, especially in a patient's vertebrae and ribs); paraparesis or paraplegia due to pressure on his spinal cord by tumour extending from his vertebrae (in Africa it is the commonest primary tumour to do this); amyloid disease of his liver, gut, cerebrovascular system, or kidneys.
PROGNOSIS. Untreated, most patients die in 6 months to 3 years. Melphalan or cyclophosphamide with prednisone increase the average survival from 17 to 52 months.
MANAGEMENT. Establish the diagnosis. Treat his anaemia by transfusion. Treat infection of his chest and urinary tract. Decide if chemotherapy is possible, or worthwhile, in relation to other needs for drugs. Ask him to drink large quantities of fluids indefinitely.
If he appears to have only one tumour (solitary myeloma), you will probably be able to find other deposits, if you look hard enough. If there really is only one deposit, and it is affecting vital structures, remove it, if you can, and give him chemotherapy. Otherwise, manage it like myelomatosis.
CHEMOTHERAPY. Give him cyclophosphamide 1 to 1.5 g/m['2] intravenously on day 1. Give him prednisolone 60 mg/m['2] on days 1 to 5. Or, give him melphalen 10 mg/m['2] by mouth on days 1 to 4, and prednisolone 60 mg/m['2] by mouth on days 1 to 4. Repeat the course every 3 to 4 weeks for one year.
Adequate hydration will correct renal failure in some patients. Give him frusemide when necessary. If he has hypercalcaemia give him steroids.
TUMOURS OF THE SKIN AND SUBCUTANEOUS TISSUE