MULTIPLE MYELOMA

also called plasma cell myeloma or myelomatosis malignant tumours of the bone marrow that usually occur during middle age or later. Myelomas are slightly more common in males and affect mostly the flat bones (e.g., ribs, sternum, pelvis, shoulder blades) and vertebrae. The disease occurs when B lymphocytes or their precursors multiply into clones of cancerous plasma cells that develop into tumours. These tumours then produce large quantities of a slightly abnormal antibody. This antibody, called myeloma protein, has no infection-fighting capability and replaces most healthy antibodies in the blood. When the tumours occur in multiple sites, the disease is called multiple myeloma. Myeloma proteins can collect in the tubules of the kidney and cause renal failure. Bone destruction frees calcium into the circulation, and the calcium may be redeposited in abnormal places such as the kidneys. Symptoms and signs of multiple myeloma include pain, anemia, weakness, susceptibility to infection, a tendency to hemorrhage, shortness of breath, and kidney insufficiency. Pathological bone fractures may occur, and neurological symptoms may follow the collapse of affected vertebrae. The disease is progressive, and prognosis is quite poor. Chemotherapy and radiation are the most common treatments. In the presence of multiple lesions, only symptomatic treatment is possible; when only one lesion is present, irradiation or surgery may arrest or cure the disease.