Revised and latest Multiple myeloma diagnostic criteria [ Revised International Myeloma Working Group (IMWG) ]
The revised IMWG criteria allow, in addition to the classic CRAB features, three “myeloma defining events” (MDEs).
The presence of at least one of these markers is considered sufficient for a diagnosis of multiple myeloma, regardless of the presence or absence of symptoms or CRAB features.
Each of these markers has been associated with an approximately 80% or higher risk of developing myeloma-related organ damage within two years.
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The new definition of active multiple myeloma is:
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Clonal bone marrow plasma cells ≥10% or biopsy-proven bony or extramedullary plasmacytoma and any one or more of the following CRAB features and myeloma-defining events:
- Evidence of end organ damage that can be attributed to the underlying plasma cell proliferative disorder, specifically:
A) Hypercalcemia: serum calcium >0.25 mmol/L (>1mg/dL) higher than the upper limit of normal or >2.75 mmol/L (>11mg/dL)
B ) Renal insufficiency: creatinine clearance <40 mL per minute or serum creatinine >177µmol/L (>2mg/dL).
C ) Anemia: hemoglobin valure of >20g/L below the lowest limit of normal, or a hemoglobin value <100g/L
D)Bone lesions: one or more osteolytic lesion on skeletal radiography, CT, or PET/CT.
If bone marrow has <10% clonal plasma cells, more than one bone lesion is required to distinguish from solitary plasmacytoma with minimal marrow involvement.
Any one or more of the following biomarkers of malignancy (MDEs ;Myeloma Defining Events):
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60% or greater clonal plasma cells on bone marrow examination.
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Serum involved / uninvolved free light chain ratio of 100 or greater, provided the absolute level of the involved light chain is at least 100mg/L (a patient’s “involved” free light chain—either kappa or lambda—is the one that is above the normal reference range; the “uninvolved” free light chain is the one that is typically in, or below, the normal range).
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More than one focal lesion on MRI that is at least 5mm or greater in size.