International Myeloma Working Group diagnostic criteria for MM and related disorders
| Disorder . | Definition . |
|---|---|
| Non-IgM MGUS | All 3 criteria must be met |
| Serum monoclonal protein (non-IgM type) <3 g/dL | |
| Clonal bone marrow plasma cells <10%* | |
| Absence of end-organ damage, such as hypercalcemia, renal insufficiency, anemia, and bone lesions that can be attributed to the plasma cell proliferative disorder | |
| SMM | Both criteria must be met: |
| Serum monoclonal protein (IgG or IgA) 3 g/dL, or urinary monoclonal protein 500 mg/24 h, and/or clonal bone marrow plasma cells 10% to 60% | |
| Absence of myeloma-defining events or amyloidosis | |
| MM | Both criteria must be met: |
| Clonal bone marrow plasma cells 10% or biopsy-proven bony or extramedullary plasmacytoma | |
| Any 1 or more of the following myeloma-defining events: | |
| Evidence of end-organ damage that can be attributed to the underlying plasma cell proliferative disorder, specifically: | |
| Hypercalcemia: serum calcium >25 mmol/L (>1 mg/dL) higher than the upper limit of normal or >275 mmol/L (>11 mg/dL) | |
| Renal insufficiency: creatinine clearance <40 mL/min or serum creatinine >177 μmol/L (>2 mg/dL) | |
| Anemia: hemoglobin value >2 g/dL below the lower limit of normal or a hemoglobin value <10 g/dL | |
| Bone lesions: ≥1 osteolytic lesion on skeletal radiography, CT, or PET/CT | |
| Clonal bone marrow plasma cell percentage 60% | |
| Involved/uninvolved serum FLC ratio 100 (involved FLC level must be 100 mg/L) | |
| >1 focal lesion on MRI studies (≥5 mm in size) |
| Disorder . | Definition . |
|---|---|
| Non-IgM MGUS | All 3 criteria must be met |
| Serum monoclonal protein (non-IgM type) <3 g/dL | |
| Clonal bone marrow plasma cells <10%* | |
| Absence of end-organ damage, such as hypercalcemia, renal insufficiency, anemia, and bone lesions that can be attributed to the plasma cell proliferative disorder | |
| SMM | Both criteria must be met: |
| Serum monoclonal protein (IgG or IgA) 3 g/dL, or urinary monoclonal protein 500 mg/24 h, and/or clonal bone marrow plasma cells 10% to 60% | |
| Absence of myeloma-defining events or amyloidosis | |
| MM | Both criteria must be met: |
| Clonal bone marrow plasma cells 10% or biopsy-proven bony or extramedullary plasmacytoma | |
| Any 1 or more of the following myeloma-defining events: | |
| Evidence of end-organ damage that can be attributed to the underlying plasma cell proliferative disorder, specifically: | |
| Hypercalcemia: serum calcium >25 mmol/L (>1 mg/dL) higher than the upper limit of normal or >275 mmol/L (>11 mg/dL) | |
| Renal insufficiency: creatinine clearance <40 mL/min or serum creatinine >177 μmol/L (>2 mg/dL) | |
| Anemia: hemoglobin value >2 g/dL below the lower limit of normal or a hemoglobin value <10 g/dL | |
| Bone lesions: ≥1 osteolytic lesion on skeletal radiography, CT, or PET/CT | |
| Clonal bone marrow plasma cell percentage 60% | |
| Involved/uninvolved serum FLC ratio 100 (involved FLC level must be 100 mg/L) | |
| >1 focal lesion on MRI studies (≥5 mm in size) |
Adapted from Rajkumar et al9 with permission.
Bone marrow transplantation can be deferred in patients with low-risk MGUS (IgG type, M protein 15 g/L, normal FLC ratio) in whom there are no clinical features concerning for myeloma.
CT, computed tomography; MGUS, monoclonal gammopathy of undetermined significance; PET, positron emission tomography.