A 68-year-old asymptomatic man has an IgG kappa paraprotein of 1.5 g/dL on routine electrophoresis. Bone marrow aspirate shows 6 percent plasma cells with no clonal restriction by light chains. Skeletal survey, haemoglobin, calcium and creatinine are all normal, and urine protein electrophoresis is negative. What is the correct diagnosis and approximate annual rate of progression to myeloma?

• A Smouldering myeloma, about 10% per year
• B Waldenström macroglobulinaemia, about 5% per year
• C Monoclonal gammopathy of undetermined significance, about 1% per year ✓
• D Solitary plasmacytoma, about 3% per year

Explanation

MGUS is defined by serum M-protein below 3 g/dL, bone marrow clonal plasma cells below 10 percent, and absence of CRAB features or amyloidosis. Progression to myeloma or related disorder occurs at roughly 1 percent per year. Smouldering myeloma requires an M-protein of 3 g/dL or more, or clonal plasma cells of 10 percent or more, so the small spike and 6 percent plasma cells exclude option A.

Reference: Williams Hematology, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.