Multiple Myeloma Diagnostic Criteria

Myeloma Diagnostic Criteria
Clonal Marker
Clonal BM Plasma Cells ≥10%
SLiM Criteria (Myeloma-Defining Events)
S: ≥60% Bone Marrow Plasma Cells
Li: Involved/Uninvolved Free Light Chain Ratio ≥100
M: MRI with >1 Focal Lesion (≥5 mm)
CRAB Criteria (End-Organ Damage)
C: Calcium >11 mg/dL
R: Renal Insufficiency (Creatinine >2 mg/dL)
A: Anemia (Hemoglobin <10 g/dL)
B: Bone Lesions (≥1 osteolytic lesion)
Diagnosis: Does Not Meet Criteria
Does Not Meet Criteria
No clonal marker and no SLiM-CRAB features identified. Myeloma diagnosis not supported.
Diagnoses multiple myeloma, according to the International Myeloma Working Group (IMWG).

Why Use

Provides a standardized, evidence-based framework for diagnosing multiple myeloma. Facilitates early diagnosis, enabling prompt management and prevention of end-organ damage.

When to Use

Use to confirm a diagnosis of multiple myeloma in patients with signs and/or symptoms suggestive of plasma cell dyscrasia.

Formula

Selection of the appropriate criteria: Criteria (A) Clonal bone marrow plasma cells ≥10% or (B) biopsy-proven bony or extramedullary plasmacytoma AND (C) ≥1 myeloma defining event (C1 or C2): (C1) End organ damage attributable underlying plasma cell proliferative disorder, specifically: Hypercalcemia: serum calcium >1 mg/dL (>0.25 mmol/L) higher than upper limit of normal or >11 mg/dL (>2.75 mmol/L) Renal insufficiency: creatinine clearance <40 mL per min or serum creatinine >2 mg/dL (177 μmol/L) Anemia: hemoglobin >2 g/dL (20 g/L) below lower limit of normal, or hemoglobin <10 g/dL (100 g/L) Bone lesions: ≥1 osteolytic lesion on skeletal x-ray, CT, or PET-CT (C2) ≥1 of the following biomarkers of malignancy: Clonal bone marrow plasma cells ≥60% Involved:uninvolved sFLC ratio ≥100 >1 focal lesion on MRI

Pearls / Pitfalls

Concurrent conditions, such as chronic kidney disease, anemia due to other causes, or metabolic bone disease, may confound results and lead to diagnostic uncertainty or misclassification.

Advice

If the criteria are met: Initiate further staging, including cytogenetic analyses and the use of the International Staging System (ISS) or Revised International Staging System (R-ISS) , to guide treatment decisions. Refer to a hematologist/oncologist for potential initiation of treatment. Evaluate for transplant eligibility and consider supportive care measures. If criteria are not met: Monitor for progression in patients with smoldering myeloma or monoclonal gammopathy of undetermined significance (MGUS). Consider and evaluate for other diagnoses. Reassess if new symptoms or complications arise. Provide patient education about symptoms that warrant re-evaluation.

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