Pain and myeloma Flashcards
How do the morphology of normal plasma cells differ from neoplastic plasma cells?
normal: mononucleated
neoplastic: multi-nucleated, with many granules present (which would contain high amounts of light chain paraprotein)
What is MGUS?
= monoclonal gammopathy of unknown source
All myeloma patients have MGUS
But not all MGUS will be myeloma
MGUS is not itself defined as a malignancy
leads to increased infectious risk, osteoporosis.
Why is myeloma a complex illness?
- heterogenous disease
- broad clinical spectrum
- includes progression through multiple clinical stages
- Can present at any age: most commonly around 70yo, but 25% of patients are <60yo
- most myelomas contain multiple neoplastic plasma cell clones
- Dominant clone will determine (initial) treatment response
- But more resistant secondary clones may appear at later stage (reduced efficiency of treatment response over time)
What are the main clinical stages through which myeloma progresses?
- Premalignant MGUS
- Smouldering (asymptomatic) myeloma: light chains present in blood/urine but no end organ damage is present
- Symptomatic myeloma
- Relapsed and refractory myeloma (almost a certainty relapse)
- Plasma cell leukaemia (end stage disease when neoplastic plasma tumour cells leave BM and enter blood stream)
What is a plasma cell
terminally differentiated B lymphoid cell
matured in BM and LNs
plasma cels produce high affinity Ab with diverse Ag specificities
(one Ag type per cell clone)
What is the pathogenesis of myeloma?
clonal expansion of Ig-secreting plasma cells
BM-sited disease which produces lytic lesions in bone, anaemia and BM failure
- Plasma cells secrete monoclonal protein
- most commonly IgG (60%) or IgA (20-25%) or light chains only (15-20%)
Are the Ig produced by neoplastic plasma cells functional?
No
- they are essentially junk forms of normal Ig secreted by normal tissue
- light chain only means incomplete Ig structure
Note: IgM secreting tumours are more common in lymphoma
Is amyloidosis common in all types of myeloma?
Can occur in any type or even in MGUS
But it is more common in lambda than kappa light chain restricted myeloma
What is the epidemiology of multiple myeloma?
blood cancers: 5th most common cancer in UK
2x as common in African Americans
most commonly Dx in >70yo
What are the main tests used to Dx myeloma?
INITIAL
Lab tests: FBCs, U&Es, LFTs
Serum/urine protein electrophoresis: M-protein in serum and M-protein fragments in urine (Bence-Jones)
Can also use liquid chromatography to detect M-protein in serum
beta2 microglobulin
FURTHER
BM aspirate: immunophenotyping (flow cytometry), conventional cytogenetics, FISH, gene profiling
Imaging: X-ray/skeletal survey, CT, MRI and PET-TMG
What is beta-2-microglobulin and how is it used to investigate myeloma?
B2-microglobulin = part of MHC protein
In advanced stage myeloma, this is likely to be elevated
What are the main genetic abnormalities associated with myeloma?
risk loci on chromosome 1, chromosome 14 (heavy chain genes reside here), 17p deletions
Looking for DNA translocations into these key sites
How can burden/progression of myeloma affect lab tests?
high burden of disease is associated with seeing abnormalities relating to end organ damage e.g. renal failure
Anaemia can precede myeloma Dx by >2yr
Anaemia can also itself elevate ESR (FYI)
What are the IMWG criteria for myeloma? What does is distinguish?
IMWG = international myeloma working group
Dx criteria
Distinguishes MGUS, vs. smouldering myeloma vs. myeloma
What are the IMWG criteria for Dx of MGUS?
Either
1) IgG/A/M MGUS
serum M-protein >3g/dL AND clonal BM plasma cells <10% AND no myeloma defining events
OR
2) Light chain MGUS
Abnormal sFLC ration AND increased level of appropriate light chain AND no Ig heavy chain on immunofixation AND clonal BM plasma cells <10% AND urinary M-protein <500mg/24hr AND no myeloma defining events
What are the IMWG criteria for Dx of smouldering MGUS?
All of the below:
- serum M-protein >= 3g/dL OR
- urinary M-protein >= 500mg/24h
- clonal BM plasma cells 10-60%
- no myeloma defining events or amyloidosis
What are the IMWG criteria for Dx of Multiple Myeloma?
- clonal BM plasma cells >10% OR
- Biopsy proven body or extramedullary plasmacytoma
AND - 1 or more myeloma defining features
What are the myeloma defining features as defined as CRAB?
C: hypercalcaemia
R: renal insufficiency/failure
A: anaemia
B: bony lytic lesions and pain
What are the myeloma defining features as defined as SLiM?
These are only referred to in the absence of CRAB criteria
S: ≥60% clonal BM plasma cells; Li: serum free Light chain ratio involved:uninvolved ≥100;
M: >1 focal lesion (≥5 mm each) detected by MRI studies
When would smouldering myeloma be treated?
Updated IMWG criteria
- high risk smouldering myeloma with 70-80% chance of disease progression in 2 yr
SLiM criteria must be met
Ratio of abnormal : normal light chain. If > 100 then treat
What is the pattern or remission and relapse associated with myeloma?
asymptomatic (smouldering)
symptomatic
relapsing
refractory
How does relapse and remission correlate with therapy line in myeloma?
Duration of remission reduces with each line of therapy
Myeloma becomes progressively more resistant to therapy
As remaining clones are more and more treatment resistant
Given the high relapse rate, how is Rx for myeloma approached?
first line therapy is most important and targeted
As this can greatly inform general prognosis
How can pain present in myeloma?
- Pain caused by disease (bone pain, nerve pain, spinal cord compression)
- Pain caused by treatment (peripheral neuropathy)
How is bone disease in myeloma managed?
imaging, ID of bone disease cause
Rx:
pain control, radiotherapy/cheo with steroids, surgery, bisphosphonates
What is the role of imaging in myeloma Mx?
Dx: asymptomatic myeloma
important for evaluation of spinal disease
important in monitoring: non-secretory, oligo-secretory and extra-medullary disease
Why may surgery in myeloma be indicated?
high risk of pathological fracture (reduced bone strength, lytic lesions)
e.g. pin insertion or cement to stabilise spinal column
this can also help as part of pain control
Why is imaging particularly important in non-secretory myeloma?
non-secretory = no secreted paraprotein or light chain fragments, so won’t be able to detect these in serum/urine
other Ix such as imaging become more important for Dx
What are the NICE guideline re: imaging in myeloma?
- offer imagine to all patients - with suspected myeloma
- whole body MRI is first line iii available (most centres don’t have access to this however)
- whole-body low dose CT (shows bone only as no contrast) can be used as an alternative
- skeletal survey to be used as third line (or if MRI/CT are unsuitable)
- Isotope bone scans are not used