An asymptomatic 68-year-old man has serum IgG kappa monoclonal protein of 38 g/dL. Bone marrow shows 14% clonal plasma cells. Hemoglobin, calcium, creatinine, and skeletal survey are normal, and urine free light chains are not elevated. What is the correct classification?
- A MGUS, observation only
- B Symptomatic multiple myeloma requiring induction therapy
- C Smoldering multiple myeloma, close monitoring without immediate therapy ✓
- D Solitary plasmacytoma requiring radiotherapy
Correct answer: C. Smoldering multiple myeloma, close monitoring without immediate therapy
Explanation
Smoldering multiple myeloma requires serum M-protein of 30 g/dL or more, or clonal plasma cells of 10 percent or more, in the absence of myeloma-defining events (CRAB features or biomarkers such as free light chain ratio above 100). This patient meets the M-protein threshold but has no end-organ damage, so standard practice is surveillance. In MGUS the M-protein stays below 30 g/dL with fewer than 10 percent marrow plasma cells.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.