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| Myeloma | ||
| Etiology •Unknown. | ||
| Pathogenesis •Clinically, myeloma presents either because of the local effects of tumor, or by the effects of the paraprotein synthesis. •Local effects include bone pain and pathological fractures. •In addition, the replacement of the marrow by the tumor can result in anemia. •Reduction in white blood cell formation by the marrow can result in an increase in the frequency and severity of infections. •The paraprotein may result in hyperviscosity symptoms (lethargy, abnormal bleeding). •The paraprotein also results in increased turnover of normal serum immunoglobulin, so that antibody mediated defence against infectious agents is impaired. •The paraprotein effects also include symptoms due to excretion of the protein in the kidney, followed by renal damage due to cast formation in the tubules. •Amyloid deposition due to the light chains is a frequent complication of multiple myeloma. •The lytic lesion is believed to be due to activation of osteoclasts by cytokines liberated by the plasma cells. These cytokines include IL-1 and TGF-beta. •IL6 may be produced primarily by stromal cells, activated by the plasma cells. •IL6 levels are used to measure progress of the tumor., | ||
| Epidemiology •The tumor primarily affects individuals in the sixth and seventh decades of life. •Males and females are approximately equally affected. | ||
| General Gross Description •Myeloma, also known as multiple myeloma is a malignant tumor of plasma cell origin. •Grossly, myeloma is typified by multiple round deposits in various bones and soft tissues of the body. •These deposits are typically soft, gelatinous tan-white masses that are sharply demarcated. •The most frequently affected is the spine, followed by skull, pelvis, lung bones. •Examples: | ||
| General Microscopic Description •Microscopically, lesion is characterized by plasma cells, which may look like normal plasma cells, or may show various levels of atypia. •Examples: | ||
| Clinical Correlation •Characteristic of multiple myeloma is the presence of an abnormal, monoclonal antibody peak on serum electrophoresis. •In some instances, the plasma cells do not make complete immunoglobulin molecules. In such cases, the light chains made can be excreted in measurable quanitities in urine as Bence Jones protein. •X-ray of affected bone shows characteristic sharply defined "punched out" lesions that are purely lytic. •The prognosis is dismal, with few, if any, survivors at five years. | ||
| References • Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th edition. Philadelphia, W.B. Saunders, 1994, pp. 663. Please be patient during transfer. Medline will open in a new window. To return, close the Medline Window Myeloma
| Synopsis by: T.V. Rajan M.D. Ph.D. (T1X500M97303)[80]
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