A discrete, presumably solitary mass of neoplastic plasma cells in bone or in one of various extramedullary sites; in humans, such lesions are probably the initial phase of developing plasma cell myeloma. [plasmacyte + G. -oma, tumor]
* * *
plas·ma·cy·to·ma also plas·mo·cy·to·ma .plaz-mə-sī-'tō-mə n, pl -mas also -ma·ta -mət-ə a myeloma composed of plasma cells
* * *
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 melphalan and cyclophosphamide; the bone tumours are less responsive. Tumours originating in soft tissue (usually the airways) may spread to bone, producing an appearance on X-ray identical to myeloma deposits; these secondary growths often resolve completely after treatment.
* * *
plas·ma·cy·to·ma (plaz″mə-si-toґmə) [plasmacyte + -oma] 1. plasma cell dyscrasias. 2. solitary myeloma.Medical dictionary. 2011.