Myelomas Flashcards
What is myeloma?
Myelomais a cancer of a specific type of plasma cell where there is agenetic mutationcausing it to rapidly and uncontrollably multiply
These plasma cells produce one type ofantibody (immunoglobulin)
What is the median age of diagnosis of myeloma?
65
What are some risk factors for myeloma?
- Male sex
- Black African ethnicity
- Family history
- Obesity
How are myelomas classified?
Based on the isotype of antibody produced
What are some classes of myeloma?
- IgG
- IgD
- Bence-Jones myeloma
- Non-secretory myeloma
- IgA
- Biclonal
- IgE
Describe the formation of myeloma
Myeloma follows the double hit hypothesis
Normal plasma cells will recieve a genetic hit, leading to MGUS (Monoclonal gammopathy of undetermined significance)
Another hit from external factors will lead to asymptomatic myeloma, which can progress into overtly malignant myeloma
What does MGUS stand for?
Monoclonal gammopathy of undetermined significance
What is MGUS?
MGUS is the premalignant form of myeloma
What causes MGUS?
Genetic mutation
How is MGUS diagnosed?
Small increase in paraprotein
Bone marrow plasma cells <10%
- Normal calcium
- Normal renal function
- Normal haemoglobin
- No lytic lesions
- No increase in infections
How is MGUS managed?
Screening for myeloma progression
How does myeloma affect the body?
Direct tumour cell effects
Paraprotein mediated effects
What are some direct tumour cell defects of myeloma?
Bone lesions
Increased calcium
Bone pain
Marrow failure -> Anaemia
What are some paraprotein mediated effects of myeloma?
- Renal failure
- Immune suppression
- Hyperviscosity
- Amyloid
What are some possible complications of myeloma?
- Sepsis
- Hypercalcaemia and dehydration
- Hyperuricaemia
- Amyloid
What are some baseline tests performed in suspected myeloma?
- Bloods - FBC, U+Es and creatinine, calcium, CRP, plasma viscosity
- Serumprotein electrophoresis - shows the type of paraprotein
- Plain x-ray of symptomatic areasW
What are some diagnostic tests used after baseline testing in myeloma?
- Bone marrow aspirate and trephine biopsy, with plasma cell phenotyping
- Immunofixation of serum and urine to confirm and show the subtype of the paraprotein
- Skeletal survey (Whole-body MRI first line, whole body low dose CT can be used if MRI unsuitable)
- Other tests to estimate tumour burden and prognosis e.g. FISH, serum beta-2 microglobulin concentration
What is the most common type of antibody found as a paraprotein?
IgG
What is myeloma bone disease?
The disregulation of bone remodelling, leading to typical lytic lesions, usually seen in the spine, skull, long bones and ribs
What causes myeloma bone disease?
Myeloma cells can bind to marrow stromal cells, which causes the release of IL-6
This can cause osteoclast activation and osteoblast suppression, leading to increased bone lysis and thus fractures
This causes a rise in Ca2+ levels in the blood
Soft tissue plasmacytomas also occur and they are the usual cause of spinal cord compression
IL-6 and TGFß can also stimulate further myeloma cell proliferation
What is the usual management of myeloma bone disease?
Bisphisphonates
How does renal disease occur in myeloma?
This occurs by reaction of excess light chains in the thick ascending limb of the loop of Henle with Tamm-Horsfall proteins, causing the production of a cast (Cast nephropathy)
How can renal failure in myeloma be managed?
Damage may be reversible with prompt treatment with hydration, stopping nephrotoxic drugs and using drugs which switch off light chain production such as chemotherapy or steroids
What is the purpose of treatment in myeloma?
Myeloma is currently seen as an incurable chronic disease
Treatment is therefore used to improve quality of life and prolong survival
