Multiple myeloma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Multiple myeloma is a disorder affecting post germinal center B lymphocytes. A chromosomal translocation between the immunoglobulin heavy chain gene and one of many oncogenes leads to dysregulated multiplication of plasma cells. This leads to a localized damage, resulting in punched out bony lesions as well as various organ damage among other symptoms.
Pathophysiology
- Multiple myeloma develops in post-germinal center B lymphocytes
- Proliferation of a plasma cell clone and genomic instability leads to further mutations and translocations
- Production of cytokines (especially IL-6) by the plasma cells causes much of their localised damage, such as osteoporosis, and creates a microenvironment in which the malignant cells thrive. Angiogenesis (the attraction of new blood vessels) is increased
- The produced antibodies are deposited in various organs, leading to renal failure, polyneuropathy and various other multiple myeloma associated symptoms
Genetics
- A genetic mutation results in dysregulation of the oncogene which is thought to be an important initiating event in the pathogenesis of multiple myeloma
- A chromosomal translocation between the immunoglobulin heavy chain gene (on the fourteenth chromosome, locus 14q32) and an oncogene (often 11q13, 4p16.3, 6p21, 16q23 and 20q11[1]) is frequently observed in patients with multiple myeloma
- The chromosome 14 abnormality is observed in about 50% of all cases of myeloma. Deletion of (parts of) the thirteenth chromosome is also observed in about 50% of cases
Gross Pathology
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Vertebras in multiple myeloma
(Image courtesy of Melih Aktan M.D.) -
Calvarium in multiple myeloma.
(Image courtesy of Melih Aktan M.D.)
Microscopic Pathology
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Multiple Myeloma slide showing plasma cells with large nucleus and scant cytoplasm [2]
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Bone marrow aspiration in multiple myeloma.
(Image courtesy of Melih Aktan M.D.) -
Bone marrow biopsy in multiple myeloma.
(Image courtesy of Melih Aktan M.D.) -
Bone marrow in multiple myeloma.
(Image courtesy of Melih Aktan M.D.) -
Bone marrow in multiple myeloma.
(Image courtesy of Melih Aktan M.D.)
References
- ↑ Kyle RA, Rajkumar SV. Multiple myeloma. N Engl J Med 2004;351:1860-73. PMID 15509819.
- ↑ http://picasaweb.google.com/mcmumbi/USMLEIIImages