n. a malignant tumour of plasma cells, often known as a ‘solitary myeloma’. Although usually occurring as a single tumour in bone marrow or more rarely soft tissue (extramedullary plasmacytoma), it may be multiple, in which case it is classified as a multiple myeloma. All of these tumours may produce the abnormal gammaglobulins that are characteristic of myeloma, and they may progress to widespread myeloma. The soft-tissue tumours often respond to radiotherapy and to such drugs as thalidomide and cyclophosphamide; the bone tumours are typically less responsive.
(multiple myeloma, myelomatosis) n. a malignant disease of the bone marrow, characterized by two or more of the following criteria: (1) the presence of an excess of abnormal malignant plasma cells in the bone marrow; (2) typical *lytic deposits in the bones on X-ray, giving the appearance of holes; (3) the presence in the serum of an abnormal gammaglobulin, usually IgG (an immunoglobulin; see paraprotein). *Bence-Jones protein may also be found in the serum or urine. The patient may complain of tiredness due to anaemia and of bone pain and may develop pathological fractures. Treatment is usually with such drugs as steroids, melphalan, cyclophosphamide, or thalidomide with local radiotherapy to particular areas of pain. See also plasmacytoma.... myeloma
antibody-producing cells found in blood-forming tissue and also in the epithelium of the lungs and gut. They develop in the bone marrow, lymph nodes, and spleen when antigens stimulate B *lymphocytes to produce the precursor cells that give rise to them. Malignant proliferation of plasma cells results in either a *plasmacytoma or multiple *myeloma.... plasma cells
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