A 68-year-old man is found to have serum protein electrophoresis showing an M-protein of 3.2 g/dL (IgG kappa), bone marrow plasma cells 12%, but NO lytic lesions, no anaemia, and no renal insufficiency. Urine SFLC ratio is 4 (normal). This best fits which diagnosis and what is the appropriate management?
- A MGUS; observation only, no treatment
- B Smouldering multiple myeloma (SMM); observation unless specific high-risk features ✓
- C Active multiple myeloma; start VRd (bortezomib, lenalidomide, dexamethasone)
- D Solitary plasmacytoma; local radiotherapy
Explanation
Smouldering multiple myeloma (SMM) is defined by: serum M-protein ≥3 g/dL OR urine M-protein ≥500 mg/24h OR bone marrow plasma cells 10-60%, WITHOUT CRAB criteria (calcium elevation, renal insufficiency, anaemia, bone lesions) or biomarkers of malignancy (BMPC ≥60%, SFLC ratio ≥100, >1 focal MRI lesion). This patient meets SMM criteria (M-protein 3.2, BMPC 12%). Standard SMM is observed; high-risk SMM (PETHEMA model or Mayo 2018 high-risk) may benefit from early intervention. Active myeloma requires CRAB or SLiM-CRAB criteria. MGUS requires M-protein <3 g/dL and BMPC <10%.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.