smoldering myeloma

Introduction

Definition:

• presence of monoclonal paraprotein (an M-spike of >3 g/dL) or free light chain (Bence Jones protein) in the urine > 500 mg/24 hours
• bone-marrow plasmacytosis greater than 10%-59%, or both
• absence of symptoms, anemia, lytic bone lesions, hypercalcemia, or renal insufficiency

Laboratory

• complete blood count (CBC)
  • no anemia
• serum calcium: no hypercalcemia
• serum creatinine: no renal insufficiency
• serum protein electrophoresis
• serial evaluation every 3-6 months

Radiology

• radiographic survey, including long bones & skull
  • may detect lytic lesions
• whole body MRI if radiology negative to evaluate smoldering multiple myeloma
  • no lytic lesions
• bone scan not recommended
  • multiple myeloma lesions are often purely lytic
  • a bone scan detects osteoblastic lesions

Complications

• progression to active muliple myeloma or to AL-amyloidosis (57% overall)
• 10% yearly during years 1 to 5
• 3% yearly during years 6 to 10
• 1% yearly thereafter
• 5-year median rates of disease progression
  • 15% for the M-spike-only
  • 43% for >10%-plasmacytosis-only
  • 69% for the group with both

Management

• observe, do not treat
• evaluation every 3-6 months

More general terms

• multiple myeloma; plasmacytoma/plasma cell myeloma