A 70-year-old with fatigue and back pain has serum protein electrophoresis showing an M-spike in the gamma region. Bone marrow biopsy shows 35% plasma cells. No lytic lesions, hypercalcemia, renal failure, or anemia. According to the IMWG 2014 criteria, this patient's diagnosis is:

• A Monoclonal gammopathy of undetermined significance (MGUS)
• B Multiple myeloma requiring treatment
• C Solitary plasmacytoma of bone
• D Smoldering multiple myeloma (SMM) ✓

Explanation

Smoldering multiple myeloma (SMM) is defined by IMWG 2014 criteria as serum M-protein ≥3 g/dL OR urinary M-protein ≥500 mg/24h AND/OR 10–60% clonal bone marrow plasma cells, without myeloma-defining events (CRAB criteria: hyperCalcemia, Renal insufficiency, Anemia, Bone lesions) or amyloidosis. This patient has 35% plasma cells without CRAB features, fitting SMM. MGUS requires <3 g/dL M-protein and <10% plasma cells; active myeloma requires CRAB criteria or ≥60% plasma cells.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.