Multiple myeloma is an incurable bone marrow malignancy that is belongs to the B-cell lymphomas.
Characteristic is the monoclonal proliferation of plasma cells in the bone marrow, which leads to an above-average production of monoclonal immunoglobulins (IgG, IgA, IgD, IgM or IgE) and / or Bence-Jones proteins. Multiple myelomas are categorized according to the form of the secreted immunoglobulins.
IgG myelomas are the most common at about 50% of the cases, followed by a myeloma with IgA secretion and light chain myelomas, where only incomplete immunoglobulins (free light chains, Bence Jones proteins) are formed.
The term multiple myeloma refers to a diffuse infiltration of the bone marrow, while "plasmocytoma" stands for solitary plasma cell proliferation. Mostly, however, both terms are used synonymously.
The MM is typically a disease of the elderly, the peak incidence for the age of onset is between the 50th and 70th year of life. Men are slightly more affected than women.
There is no known clear risk behavior that would favor a myeloma. An exposure to ionizing radiation and pesticides may increase the risk of one. Various genetic translocations, obesity and chronic infections are also considered potential risk factors, but their influence has not yet been sufficiently clarified.
The disease is somtimes preceded by a monoclonal gammopathy of unclear significance (MGUS), here there is a risk of progression to a treatment-related MM in about 1% / year.
The overproduced proteins are deposited mostly in the kidney and lead to renal insufficiency. Bone marrow suppression of the other hematopoietic lineages leads to anemia and increased susceptibility to bacterial infections.
Multiple myeloma also causes bone pain and hypercalcaemia due to osteolysis and pathological fractures.