Multiple Myeloma and related plasma cell disorders Flashcards
Define multiple myeloma
Malignancy of bone marrow plasma cells, the terminally differentiated and immunoglobulin (Ig) secreting B cells
What is seen in myeloma causing plasma cells?
Home and infiltrate the bone marrow
May form bone expansile or soft tissue tumours: plasmacytomas
Produce a serum monoclonal IgG or IgA: paraprotein or M-spike
Produce excess of monoclonal serum free light chains
Bence Jones protein: urine monoclonal free light chains
What are the risk factors for multiple myeloma?
Obesity Age Men Black > caucasian and asian Genetics
What always precedes myeloma?
A premalignant condition: Monoclonal Gammopathy of Uncertain Significance (MGUS)
What is monoclonal gammopathy of uncertain significance?
Presence of monoclonal antibody paraprotein / M-protein in the blood or urine
What are the diagnostic criteria for MGUS?
Serum M-protein <30g/L
Bone marrow clonal plasma cells <10%
No lytic bone lesions
No myeloma-related organ or tissue impairment
No evidence of other B-cell proliferative disorder
What does IgG or IgA MGUS progress to?
Myeloma
What does IgM MGUS progress to?
Lymphoma
What other conditions are those with MGUS at risk of?
Osteoporosis
Thrombosis
Bacterial infection
Shorter life expectancy
What is the average risk of progression for MGUS?
1% annually
What is the risk stratification used for MGUS?
Mayo criteria - risk factors
Non-IgG M-spike
M-spike >15g/L
Abnormal serum free light chain (FLC) ratio
What is smouldering myeloma?
Pre-malignant disease for multiple myeloma
What criteria must be met for smouldering myeloma?
Serum monoclonal protein (IgG or IgA) >= 30g/L or urinary monoclonal protein >= 500mg per 24 hr and/or clonal bone marrow plasma cells 10-60
How does bone destruction occur in multiple myeloma?
Myeloma cells interact with bone marrow microenvironment
What is the result of bone destruction in multiple myeloma?
Destruction of bone leads to calcium in the blood and lytic lesions
What are the other results of the myeloma cells interacting with bone marrow microenvironment?
Angiogenesis
Anaemia
Immunosuppression and infections
What is the diagnostic criteria for multiple myeloma?
> 10% plasma cells in bone marrow or plasmacytoma >1 CRAB or MDE
What are the features of CRAB as a diagnostic indicator for multiple myeloma?
C: Hypercalcaemia - calcium >2.75mmol/L
R: Renal disease - creatinine >177umol/L or eGFR <40ml/min
A: Anaemia - Hb <100g/L or drop by 20g/L
B: bone disease - one or more bone lytic lesions in imaging
What are the 2014 Myeloma Defining Events (MDE)?
Bone marrow plasma cells >60%
Involved: uninvolved FLC ratio >100
>1 focal lesion in MRI (>5mm)