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Multiple Myeloma Diagnostic Criteria

Applies IMWG clonal plasma cell and CRAB/SLiM criteria to establish a diagnosis of multiple myeloma.

Multiple Myeloma Diagnostic Criteria
Clonal bone marrow plasma cells
%
Biopsy-proven bony or extramedullary plasmacytoma
Hypercalcemia (calcium >11 mg/dL or >1 mg/dL above ULN) attributable to myeloma
Renal insufficiency (creatinine >2 mg/dL or creatinine clearance <40 mL/min) attributable to myeloma
Anemia (hemoglobin <10 g/dL or >2 g/dL below normal) attributable to myeloma
≥1 osteolytic bone lesion on imaging
Involved:uninvolved serum free light chain ratio ≥100 (with involved FLC ≥100 mg/L)
>1 focal lesion ≥5 mm on MRI
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When to use

  • Distinguishing symptomatic multiple myeloma from smoldering myeloma or MGUS at initial presentation.

Formula

Diagnosis requires ≥10% clonal bone marrow plasma cells (or biopsy-proven plasmacytoma) PLUS ≥1 myeloma-defining event: any CRAB feature (hyperCalcemia, Renal insufficiency, Anemia, Bone lesions) OR any SLiM biomarker (≥60% clonal plasma cells, FLC ratio ≥100, >1 focal MRI lesion).

Pearls and pitfalls

  • The SLiM biomarkers were added in 2014 to permit earlier treatment before irreversible end-organ damage occurs.

References

  1. Rajkumar SV, et al. Lancet Oncol. 2014;15(12):e538-e548.