A 58-year-old man is diagnosed with multiple myeloma. He is transplant-eligible with good performance status. Which initial finding would shift the prognosis to high-risk myeloma requiring more aggressive therapy per the R-ISS staging system?
- A Serum beta-2 microglobulin > 5.5 mg/L with albumin < 3.5 g/dL
- B del(17p) on FISH or t(14;16) with elevated LDH ✓
- C Presence of lytic bone lesions on skeletal survey
- D Serum free light chain ratio > 100
Correct answer: B. del(17p) on FISH or t(14;16) with elevated LDH
Explanation
The Revised International Staging System (R-ISS) for multiple myeloma classifies stage III as ISS stage III (β2M > 5.5 + albumin < 3.5) PLUS high-risk cytogenetics by FISH (del17p, t(4;14), t(14;16)) AND/OR elevated LDH. The high-risk cytogenetic abnormalities del(17p) and t(14;16) independently confer poor prognosis under R-ISS regardless of other parameters. Option A alone defines ISS stage III but is R-ISS stage II without the cytogenetic component.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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