A 58-year-old man with newly diagnosed multiple myeloma has serum beta-2 microglobulin of 5.8 mg/L and serum albumin of 3.2 g/dL. FISH analysis shows del(13q) as the sole abnormality. According to the Revised International Staging System (R-ISS), what stage is he classified as?
- A R-ISS Stage II or III depending on LDH level ✓
- B R-ISS Stage II
- C R-ISS Stage III
- D R-ISS Stage I
Correct answer: A. R-ISS Stage II or III depending on LDH level
Explanation
R-ISS Stage III requires beta-2 microglobulin ≥5.5 mg/L PLUS either high-risk cytogenetics (del(17p), t(4;14), or t(14;16)) OR elevated LDH. This patient has beta-2 microglobulin 5.8 mg/L (ISS III threshold met) and del(13q) alone, which is not high-risk by R-ISS criteria. Without high-risk cytogenetics, he needs elevated LDH to be Stage III; otherwise he is R-ISS Stage II. Del(13q) alone does not confer high-risk status in R-ISS.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.