Haem: Plasma cell myeloma and MGUS Flashcards
What is the primary job of plasma cells?
To produce immunoglobulins and antibodies
What is myeloma essentially?
cancer of very mature B cells
How are plasma cells produced?
Centroblasts mature in the lymph nodes and are stimulated by antigens to turn into plasmablasts
Plasmablasts are then refined to perfectly fit the antigens they were exposed to
They downregulate and upregulate certain transcription factors
These plasmablasts eventually turn into plasma cells
What is MGUS?
Pre malignant condition. While only 1-2% of these annually progress onto myeloma, all myeloma definitely spring from MGUS.
What are the 2 most common haematopoietic malignancies?
B cell lymphomas
MGUS
What is the biochem of MGUS?
Monoclonal serum protein (IgG/ IgA) < 30g/L
Bone marrow plasma cells < 10%
Annual risk to progression of multiple myeloma is 1-2%
This is rare in young, increasing incidence with age (5% < 70 years)
What symptoms does MGUS have?
None
What is the biochem of smouldering myeloma?
Monoclonal serum protein (IgG/ IgA) ≥ 30g/L
Bone marrow plasma cells ≥ 10%
Annual risk of progression to multiple myeloma is 10%
What is the pnemonic for MGUS diagnosis?
CRAB
Calcium high
Renal impairment
Anaemia
Bone lesions
+ monoclonal protein
What kind of bone lesions do you find in myeloma?
Osteolytic
What are the 2 medical emergencies of myeloma?
Spinal cord compression
Hypercalcaemia
How to diagnose spinal cord compression?
MRI
Ig studies
FLC
What to do for spinal cord compression?
Dexamethasone
What criteria is used for MGUS?
Mayo
What is the most common cytogenetic abnormality in myeloma?
Hyper diploid karyotype
Name 2 events that happens in the tumour microenvironment?
Increased angiogenesis
Increased bone resorption
How is myeloma diagnosed?
Ig studies - Serum electrophoresis, FLC ratio, 24 hour Bence Jones urine
Bone marrow aspirate and biopsy
FISH analysis
Flow cytometry immunophenotyping
In the Bone marrow aspirate and biopsy what CD cells would you see?
CD138
Won’t see CD 19 or CD 20 as they are expressed by B cells
Which cancers are always CD 20 positive?
Lymphoma and CLL
What are the 5 ways of treating myeloma?
Cytotoxic drugs - alkylating agents Steroids Immunomodulators - Thalidomide Monoclonal antibodies - Daratumumab Proteosome inhibitors - Bortezomib
Name an alkylating agent
Melphalan
How are stem cell transplants done?
Reduced myeloma burden by drugs
Harvest stem cells from bone marrow
Single high dose Melphalan to kill myeloma cells but this will also destroy the bone marrow
Then re infuse with stem cells that were harvested
What are the 2 ways proteosome inhibitors kill myeloma cells?
Upstream effect; If the proteasome is BLOCKED, there will be accumulation of unrequired proteins. Many of these proteins will precipitate, BLOCKING cellular function.
Since myeloma cells secrete lots of immunoglobulin and paraprotein, they are susceptible to this assault on the recycling machinery and will result in myeloma cell death.
Downstream effect: If the proteasome is BLOCKED, there will be accumulation of proteins needing to be degraded. However, there will also be a shortage of amino acids/ peptides required to build new proteins. So, they CANNOT make new proteins.
How do immunomodulatory drugs work?
enhanced degradation of transcription factors (IKZF1 + IKZF3) which are required for B cell development.
What are the imaging tecnhiques used to investigate multiple myeloma?
MRI - Bone marrow infiltration
CT - small lytic lesions
PET - detects active disease
How does myeloma cause kidney injury?
FLC activate inflammatory mediators in the proximal tubule epithelium
Proximal tubule necrosis
Fanconi syndrome (renal tubule acidosis with failure of reabsorption in the proximal tubule) with light chain crystal deposition
Cast nephropathy - FLC and Bence Jones proteinurea
What is the biochem for kidney injury due to myeloma?
Serum creatinine > 177
eGFR < 40
What are the most common infections due to myeloma and why is it caused?
Viral - Herpes zoster re activation
Due to low Ig levels
What happens in myeloma and AL amyloidosis?
Misfolded FLC turn into amyloid and deposit on organs
Stain well with Congo red
Lamda light chain involved
What are the symptoms of AL amyloidosis with myeloma?
Nephrotic syndrome
Unexplained HF - Check serum FLC, High BNP, Abnormal ECG
Abnormal LFTs
Macroglossia
ED
What is MGRS?
B cell clonal lymphoproliferation where:
- > 1 kidney lesions due to Ig
- B cell clone does not cause tumour complications