Multiple myeloma

Question 1

Define multiple myeloma

Answer 1

• neoplastic clonal proliferation of plasma cells producing a monoclonal immunoglobulin
resulting in end organ dysfunction

• usually single clone of plasma cells, although biclonal myeloma also occurs. Rarely nonsecretory

Question 2

Pathophysiology of Multiple myeloma

Answer 2

malignant plasma cells secrete monoclonal antibody

ƒƒ95% produce M protein (monoclonal Ig = identical heavy chain + identical light chain, or
light chains only)
- ŠŠIgG 50%, IgA 20%, IgD 2%, IgM 0.5%
ŠŠ- 15-20% produce free light chains or light chains alone found in either:
– serum as an increase in the quantity of either kappa or lambda light chain (with an
abnormal kappa:lambda ratio)
– urine has Bence-Jones protein
ƒƒ

Question 3

Px & Cx of Multiple myeloma

Answer 3

• bone disease: pain (usually back), bony tenderness, pathologic fractures
-ƒƒ lytic lesions are classical (skull, spine, proximal long bones, ribs)
ƒƒ- increased bone resorption secondary to osteoclast activating factors such as PTHrP
• anemia: weakness, fatigue, pallor ƒƒ secondary to bone marrow suppression
• weight loss
• infections: ƒƒusually S. pneumoniae and Gram-negatives, secondary to suppression of normal plasma cell function
• hypercalcemia: N/V, confusion, constipation, polyuria, polydipsia
ƒ- secondary to increased bone turnover
• renal disease/renal failure
ƒƒmost frequently causes cast nephropathy
• bleeding
ƒƒ- secondary to thrombocytopenia, may see petechiae, purpura
- can also be caused by acquired von Willebrand disease

Question 4

How can you detect light chains in urine?

Answer 4

Need sulfosalicylic acid or 24 h urine protein for immunofixation or electrophoresis.

Routine urinalysis will not detect light chains as dipstick detects albumin

Question 5

Light chain disease in multiple myeloma

• % of MM
• major problem
• prognosis factor

Answer 5

15% of MM produce only light chains.

Renal failure is a major problem.

Kappa > lambda light chain has better prognosis.

Question 6

How do you diagnose multiple myeloma?

Answer 6

1. serum or urinary monoclonal protein
2. presence of clonal plasma cells in bone marrow or a plasmacytoma
3. presence of end-organ damage related to plasma cell dyscrasia, such as:
   - ŠŠincreased serum Ca2+
   ŠŠ- lytic bone lesions
   ŠŠ- anemia
   ŠŠ- renal failure

Question 7

Rx of multiple myeloma

Answer 7

• treatment is non-curative
• autologous stem cell transplant if 65 yr old or transplant-ineligible

• supportive management:
- ƒƒbisphosphonates for those with osteopenia or lytic bone lesions (requires renal dosing)
ƒƒ- local XRT for bone pain, spinal cord compression
ƒ- ƒkyphoplasty for vertebral fractures to improve pain relief and regain height
ƒƒ- treat complications: hydration for hypercalcemia and renal failure, bisphosphonates for
severe hypercalcemia, prophylactic antibiotics, erythropoietin for anemia, DVT prophylaxis

Question 8

Median survival of multiple myeloma

Answer 8

median survival based on stage, usually 16-70 mo