3. WHAT’S MGUS??
MGUS describes premalignant
disorder characterized by
Limited monoclonal plasma cell
proliferation
Stable monoclonal paraprotien in
serum or less commonly in urine
Absence of clinicopathological
evidence of MM,WM,AL or LPDs.
5. EPIDEMIOLOGY
Age. The risk of increases with age. The
highest incidence is among adults age 85
and older.
Race. Blacks are more likely to
experience this condition than are
whites.
Sex. more common in men than it is in
women.
Family history.
6. PATHOPHYSIOLOGY
Pathologically, the lesion in MGUS is in fact
very similar to that in multiple myeloma.
There is a predominance of clonal plasma
cells in the bone marrow with an
abnormal immunophenotype (CD38+
CD56+ CD19−) mixed in with cells of a
normal phenotype (CD38+ CD56−
CD19+); in MGUS, on average more than
3% of the clonal plasma cells have the
normal phenotype, whereas in multiple
myeloma, less than 3% of the cells have
the normal phenotype
7. Pathogenesis
Approximately 50% of patients with MGUS and SMM have
primary translocations in the clonal plasma cells
involving the immunoglobulin heavy chain (IgH)
locus on chromosome 14q32 (IgH translocated
MGUS/SMM
The most common partner chromosome loci and genes
dysregulated in these translocations are: [cyclin D1
gene]), [cyclin D3 gene])
Deletion of chromosome 13, a major prognostic factor
in multiple myeloma, is seen in up to 50% of patients
with MGUS by interphase fluorescent in situ
hybridization; hence, the presence of this abnormality
cannot be used to differentiate MGUS from multiple
myeloma
8. It is felt that these translocations are important
pathogenetically in initiating and sustaining
clonal proliferation.
The precipitating event for these translocations
may be related to infection or immune
dysregulation, and likely occurs during IgH
switch recombination or somatic hypermutation
The pathogenesis in 40%–50% of MGUS and
SMM with no evidence of IgH translocations
(IgH non-translocated MGUS/SMM) is unclear.
10. CLINICAL FEATURES
Asymptomatic
No abnormal physical findings
Incidental discovery : ESR /↑
globlin↑
Neuropathy may be ass attributed
to monoclonal gammopathy
Thrombotic events
11. INVESTIGATIONS
exclude CRAB
FBC: no anemia or other cytopenia
Chemistry : RFT, s Ca++↔
Serum protein electrophoresis:IgG 70%,IgM 15%,
IgA12%,biclonal 3%,LC<1%
Immunoglobulin quantitation :immunoparesis
SFLC:~30% have abn ĸ:λ ratio
Urine electrophoresis:
Skeletal survey:normal
Serum β2 microglobulin:normal
BMA or trephine biopsy:indicated if abn
FBC,RFT,sCa, SFLC,sk survey,non IgG
paraprotein,paraprotein>15g/L
12. DIAGNOSIS
All 4 criteria must be met :
1. Serum monoclonal protein <3g/dL
2. BM plasma cells <10%
3. No evidence of other B cell LPDs
4. No myeloma related end organ or
tissue impairment ie CRAB
18. RISK STRATIFICATION
1. Assess patient for each of three
risk factors
Abnormal serum free light chain ratio
(SFLC)
Serum M protein ≥ 1.5 g/dL
M protein not of IgG subtype
19. 2. Sum the number of risk factors
to determine risk category and
prognosis
20. MANAGEMENT
NO treatment
Follow up every 6m then annually
(FBC, renal function ,serum Ca+
+ ,serum Igs, paraprotein
quantitation ,SFLC)
24. PATHOGENESIS
Almost all have either translocation
involving IgH (50%) or
hyperdiploidy(40%)
Angiogenesis is greater than MGUS
but less than in MM
25. CLINICAL & LABORATORY
FEATURES
Absence of signs & symptoms
FBC : Hb >10 gm/dL
S. creat <130 micromol /L ,normal
s Ca++
β2 microglobulin :normal / minimal rise
BMA: >10% plasma cells
BM cytogenetics
Skeletal radiology :normal
26. DIAGNOSTIC CRITERIA
Paraprotein > 3gm/dl and / or
plasma cells in BM >10%
No evidence of other B cell LPD
No myeloma related end organ or
tissue impairment
28. RISK FACTORS FOR EARLY
PROGRESSION
Shorter time ass with:
Serum paraprotein >3g/dL
IgA protein type
Urinary BenceJones proteinuria>50mg/d
BM plasmacytosis>25%
Suppression of uninvolved Ig
SFLC<0.125 or >8
Abn MRI
29. RISK STRATIFICATION
A scoring system has been developed
using 2 parameters
1. Quantity of paraprotein <3 vs.>3 g/dL
2. Type of paraprotein IgG vs.IgA
Another scoring system using 3
parameters
1. BM plasmacytosis>10%
2. Serum M protein>3g/dL
3. SFLC ratio <0.125 or >8
30. MANAGEMENT
Chemotherapy is not indicated
No benefit for therapy before
symptomatic disease
Follow up every 3-4 months
Clinical trials early treatment with
bisphosphonate, thalidomide and
lenalidomide ??? Delay progression
Notes de l'éditeur
Pathogenesis and progression of monoclonal gammopathies.