Definition of MGUS, SMM, and symptomatic MM
| MM classification . | International Myeloma Working Group criteria, 2010 version45 . |
|---|---|
| MGUS | Serum M protein <3 g/dL |
| Light-chain restricted bone marrow plasma cells <10% | |
| No end-organ damage | |
| SMM | Serum M protein >3 g/dL |
| Ad/or light-chain restricted bone marrow plasma cells >10% | |
| Or urinary monoclonal protein >500 mg per 24 hr | |
| No end-organ damage | |
| MM | Clonal bone marrow plasma cells ≥10% and/or biopsy-proven plasmacytoma |
| Presence of serum and/or urinary monoclonal protein at any level | |
| Evidence of end-organ damage that can be attributed to the underlying plasma cell proliferative disorder (CRAB criteria): hypercalcemia, serum calcium >0.25 mmol/L above upper limit of normal or >2.75 mmol/L (>1 mg/dL above upper limit of normal); renal insufficiency, serum creatinine >173 μmol/L (>2 mg/dL); anemia, normochromic, normocytic with a hemoglobin value of >2 g/dL below the lower limit of normal or a hemoglobin value <10 g/dL; bone lesions, lytic lesions or osteoporosis with compression fractures | |
| New definition of MM requiring therapy | Clonal bone marrow plasma cells ≥10% or biopsy proven plasmacytoma and |
| Any CRAB criteria as described above | |
| Or any myeloma defining events (MDE) as follows: clonal bone marrow plasma cell percentage* ≥60%47 ; an abnormal FLC ratio ≥100 (involved κ) or <0.01 (involved λ)48 ; and ≥2 focal lesions on MRI or PET-CT studies46,49 |
| MM classification . | International Myeloma Working Group criteria, 2010 version45 . |
|---|---|
| MGUS | Serum M protein <3 g/dL |
| Light-chain restricted bone marrow plasma cells <10% | |
| No end-organ damage | |
| SMM | Serum M protein >3 g/dL |
| Ad/or light-chain restricted bone marrow plasma cells >10% | |
| Or urinary monoclonal protein >500 mg per 24 hr | |
| No end-organ damage | |
| MM | Clonal bone marrow plasma cells ≥10% and/or biopsy-proven plasmacytoma |
| Presence of serum and/or urinary monoclonal protein at any level | |
| Evidence of end-organ damage that can be attributed to the underlying plasma cell proliferative disorder (CRAB criteria): hypercalcemia, serum calcium >0.25 mmol/L above upper limit of normal or >2.75 mmol/L (>1 mg/dL above upper limit of normal); renal insufficiency, serum creatinine >173 μmol/L (>2 mg/dL); anemia, normochromic, normocytic with a hemoglobin value of >2 g/dL below the lower limit of normal or a hemoglobin value <10 g/dL; bone lesions, lytic lesions or osteoporosis with compression fractures | |
| New definition of MM requiring therapy | Clonal bone marrow plasma cells ≥10% or biopsy proven plasmacytoma and |
| Any CRAB criteria as described above | |
| Or any myeloma defining events (MDE) as follows: clonal bone marrow plasma cell percentage* ≥60%47 ; an abnormal FLC ratio ≥100 (involved κ) or <0.01 (involved λ)48 ; and ≥2 focal lesions on MRI or PET-CT studies46,49 |
These studies are mandatory for risk stratification of patients with SMM and exclusion of patients with overt symptomatic MM or with the new classified patients with MDE.