According to the International Myeloma Foundation, the definition of MM is ≥ 10% clonal bone marrow plasma cells or a biopsy-proven plasmacytoma plus the presence of one or more calcium elevation, renal insufficiency, anemia, and bone abnormalities (CRAB) features and myeloma-defining events (MDEs).
This is a revision from the previous criteria for the diagnosis of MM that required the CRAB criteria for the presence of end-organ damage. CRAB includes increased calcium levels, renal dysfunction, anemia, and destructive bone lesions. MDE incorporates three specific biomarkers: bone marrow clonal plasmacytosis ≥ 60%, serum involved/uninvolved free light chain (FLC) ratio ≥ 100 (provided involved FLC is ≥ 100 mg/L), or more than one focal lesion on MRI (of at least 5 mm).
Smoldering multiple myeloma can have a bone marrow percentage from 10% to 60%. A bone marrow percentage of < 10% is considered monoclonal gammopathy of undetermined significance (MGUS), and > 60% is considered active myeloma.
Learn more about the management of MM.
Medscape © 2023 WebMD, LLC
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Joshua Richter, Emmanuel C. Besa. Fast Five Quiz: Multiple Myeloma Management - Medscape - May 16, 2023.