- Multiple myeloma (MM) is a malignant proliferation of a single clone of plasma cells. These malignant cells produce monoclonal protein (immunoglobulin [Ig]) that can be detected in the blood and/or urine as it is filtered in the kidneys.
- MM is characterized by bony lytic lesions, hypercalcemia, increased susceptibility to infections, and renal impairment.
- Monoclonal gammopathy of undetermined significance (MGUS) is a common disorder with limited monoclonal plasma cell proliferation that can progress to smoldering MM (SMM) or symptomatic MM at rate of ~1% per year.
- MM affects the older adults with a median age of 65 to 74 years.
- Accounts for nearly 2% of all cancers and 17% of hematologic malignancies in the United States
- African Americans about 2 to 3 times more commonly affected than Caucasians; less common in Asians
7 cases per 100,000 in the United States annually
In 2018, there were ~160,000 recognized cases worldwide.
Etiology and Pathophysiology
- It is most likely caused by genetic alteration involving chromosomal abnormalities and sporadic mutations.
- Genetic damage in developing B lymphocytes occur at time of isotype switching.
- Chromosomal abnormalities involve Ig heavy chain translocations, with cyclin D1 t(11;14) the most common, and deletion of 17p13 (p53 locus).
MM rarely occurs in familial clusters. A rare form of paratarg-7 protein might have pathogenic role.
- Most cases have no known risks associated.
- Old age; immunosuppression; and exposure to chemicals, heavy metals, and ionizing radiation increase the risk of MM.
Commonly Associated Conditions
Secondary amyloidosis can be associated with MM and polyneuropathy, organomegaly, endocrinopathy, M protein, skin changes (POEMS)
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