An asymptomatic 62-year-old man is found to have a serum IgG monoclonal protein of 38 g/dL and bone marrow plasma cells of 25%. Skeletal survey shows no lytic lesions, hemoglobin is 12.8 g/dL, creatinine is normal, corrected calcium is 9.6 mg/dL, and no MRI focal lesion is present. What is the correct classification?

• A Solitary plasmacytoma
• B Monoclonal gammopathy of undetermined significance
• C Multiple myeloma requiring immediate therapy
• D Smoldering multiple myeloma ✓

Explanation

Smoldering multiple myeloma requires an M-protein of at least 30 g/dL or marrow clonal plasma cells of at least 10 percent, together with absence of myeloma-defining events such as CRAB features or imaging focal lesions. MGUS falls below these thresholds and progresses at about 1 percent per year versus roughly 10 percent per year for smoldering disease. Solitary plasmacytoma requires a single osseous or extraosseous clone without marrow involvement.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.