A 55-year-old man with multiple myeloma has hypercalcaemia, renal failure (creatinine 3.1 mg/dL), anaemia, and more than 10% plasma cells on bone marrow biopsy. FISH shows t(4;14). Serum free light chain ratio is 200. How is this patient's disease risk classified under the R-ISS staging?
- A Staging cannot be determined without LDH and β2-microglobulin values ✓
- B R-ISS stage III — poor prognosis
- C R-ISS stage I — good prognosis
- D R-ISS stage II — intermediate prognosis
Correct answer: A. Staging cannot be determined without LDH and β2-microglobulin values
Explanation
The Revised International Staging System (R-ISS) for multiple myeloma requires both: (1) ISS stage based on serum β2-microglobulin and albumin, and (2) cytogenetic risk (FISH) and serum LDH. R-ISS stage III requires ISS stage III plus either high-risk FISH (t(4;14), t(14;16), or del(17p)) or elevated LDH. While this patient has high-risk cytogenetics (t(4;14)), the ISS stage cannot be determined without β2-microglobulin and serum albumin, and LDH is also needed. Therefore, staging cannot be definitively assigned from the information given.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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