Plasma Cell Myeloma and Amyloid and MGUS Flashcards
What are the key features of myeloma (6)
Monoclonal PCs. Anaemia. Paraprotein. Infections. Kidney failure. Osteolytic lesions.
What is multiple myeloma
It is a cancer of transformed plasma cells, terminally differentiated B cells that secrete Ig and are the effector cells of the specific humoural immune response.
What causes transformation of B cells into myeloma cells
Transformation results from a range of numeric and structural genetic aberrations that accumulate from a pre-malignant condition (MGUS) to terminal progression.
What are the two major complications of MM
Bone disease.
Renal failure.
How common is MM
It is the second most common haematopoietic malignancy (after the B cell lymphomas)
How many people are affected by MM in the UK
> 4000 people every year are affected.
What is the median survival for MM
4-7 years
It is debilitating and incurable
What are plasma cells
Plasma cells are the terminally differentiated efffector cells of the specific humoural immune response
How are mature plasma cells formed (4)
Encountering antigen drives a virgin B cell to generate a low-affinity plasma cell or stimulates its migration to a germinal centre. In the germinal centre, affinity maturation occurs and is mediated through two processes: somatic hypermutation and antigen selection. Subsequently, class switch recombination occurs, leading to the development of immunoglobulin (Ig) isotypes. Once this process is complete, the plasmablast leaves the germinal centre and migrates to the bone marrow where it becomes a long-lived plasma cell that produces antibody.
What cell in the body secretes the most proteins
Plasma cells secrete more proteins than any other cell (up to 10,000lg molecules/second)
What is the pathogenesis of MM
Genetic instability leads to monoclonal gammopathy of undetermined significance (MGUS).
1%/year of these transform to MM due to genetic alterations and changes in the bone marrow microenvironment
What genetic instability occurs to generate MGUS (2)
Translocations at 14q32 (50%)
Deletion of chromosome 13 (50%)
What genetic defects need to occur for MGUS to transform to MM (3)
N-RAS, K-RAS (30%)
p16 Methylation (40%)
Secondary translocations?
What changes occur in the bone marrow microenvironment to contribute to malignancy change of MGUS to MM (2)
Increased bone resorption
Increased angiogenesis
What karyotype suggests better prognosis in MM
55-60% of patients have a hyperdiploid karyotype, which gives a better prognosis than those with non-hyperdiploid disease.
What is the evolution of MM
Post-germinal centre B cell –> MGUS –> smouldering myeloma –> myeloma –> plasma cell leukaemia