The International Myeloma Working Group (IMWG) has reported criteria for the diagnosis of multiple myloma.

Criteria for multiple myeloma - both of the following:

(1) plasma cell proliferation (one of the following):

(1a) clonal bone marrow plasma cells >= 10%

(1b) biopsy-proven bone plasmacytoma

(1c) biopsy-proven extramedullary plasmacytoma

(2) one or more of the following:

(2a) evidence of end-organ damage including CRAB findings attributable to plasma cell proliferation

(2b) clonal bone marrow plasma cell percentage >= 60%

(2c) involved light chain >= 100 mg/L AND involved-to-uninvolved light chain ratio >= 100

(2d) 2 or more focal lesions >= 5 mm in diameter on MRI


CRAB findings:

(1) hypercalcemia (> 11 mg/dL)

(2) renal insufficiency (creatinine clearance < 40 mL per min; serum creatinine > 2 mg/dL)

(3) anemia (hemoglobin < 10 g/dL)

(4) >= 1 osteolytic bone lesions on CT or CT-PET

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