Criteria for diagnosis and risk of progression in MGUS
| Subtype of MGUS . | Diagnostic criteria . | Risk of progression . | Pattern of progression . |
|---|---|---|---|
| IgM MGUS | All 3 criteria must be met: | 1% per year | Waldenström macroglobulinemia, AL amyloidosis; rarely IgM multiple myeloma |
| • Serum IgM monoclonal protein <3 gm/dL | |||
| • Bone marrow lymphoplasmacytic infiltration <10%* | |||
| • No evidence of anemia, constitutional symptoms, hyperviscosity, lymphadenopathy, or hepatosplenomegaly that can be attributed to the underlying lymphoproliferative disorder | |||
| Non-IgM MGUS | All 3 criteria must be met: | 0.5% per year | Multiple myeloma, solitary plasmacytoma, AL amyloidosis |
| • Serum monoclonal protein (non-IgM type) <3 gm/dL | |||
| • Clonal bone marrow plasma cells <10%* | |||
| • Absence of end-organ damage such as hypercalcemia, renal insufficiency, anemia, and bone lesions (CRAB) that can be attributed to the plasma cell proliferative disorder | |||
| Light-chain MGUS | All criteria must be met: | 0.3% per year | Light-chain multiple myeloma and AL amyloidosis |
| • Abnormal FLC ratio (<0.26 or >1.65) | |||
| • Increased level of involved light chain (increased κ FLC in patients with FLC ratio >1.65 and increased λ FLC in patients with FLC ratio <0.26) | |||
| • No immunoglobulin heavy-chain expression on immunofixation | |||
| • Absence of end-organ damage that can be attributed to the plasma cell proliferative disorder | |||
| • Clonal bone marrow plasma cells <10%* | |||
| • Urinary monoclonal protein <500 mg per 24 h |
| Subtype of MGUS . | Diagnostic criteria . | Risk of progression . | Pattern of progression . |
|---|---|---|---|
| IgM MGUS | All 3 criteria must be met: | 1% per year | Waldenström macroglobulinemia, AL amyloidosis; rarely IgM multiple myeloma |
| • Serum IgM monoclonal protein <3 gm/dL | |||
| • Bone marrow lymphoplasmacytic infiltration <10%* | |||
| • No evidence of anemia, constitutional symptoms, hyperviscosity, lymphadenopathy, or hepatosplenomegaly that can be attributed to the underlying lymphoproliferative disorder | |||
| Non-IgM MGUS | All 3 criteria must be met: | 0.5% per year | Multiple myeloma, solitary plasmacytoma, AL amyloidosis |
| • Serum monoclonal protein (non-IgM type) <3 gm/dL | |||
| • Clonal bone marrow plasma cells <10%* | |||
| • Absence of end-organ damage such as hypercalcemia, renal insufficiency, anemia, and bone lesions (CRAB) that can be attributed to the plasma cell proliferative disorder | |||
| Light-chain MGUS | All criteria must be met: | 0.3% per year | Light-chain multiple myeloma and AL amyloidosis |
| • Abnormal FLC ratio (<0.26 or >1.65) | |||
| • Increased level of involved light chain (increased κ FLC in patients with FLC ratio >1.65 and increased λ FLC in patients with FLC ratio <0.26) | |||
| • No immunoglobulin heavy-chain expression on immunofixation | |||
| • Absence of end-organ damage that can be attributed to the plasma cell proliferative disorder | |||
| • Clonal bone marrow plasma cells <10%* | |||
| • Urinary monoclonal protein <500 mg per 24 h |
Adapted from Rajkumar et al1 with permission.
FLC, free light chain.
A bone marrow can be deferred in patients with small (<1.5 gm/dL) IgM MGUS, low-risk MGUS (IgG type, M- protein <1.5 gm/dL, normal free light-chain ratio), and small (involved/uninvolved serum-free light-chain ratio <8) light-chain MGUS in whom there are no clinical features concerning for myeloma or lymphoplasmacytic malignancy.