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Abstract: TH-OR069

Histologic Predictors of Renal Outcome in Myeloma Cast Nephropathy: A Multicenter Study

Session Information

Category: Pathology and Lab Medicine

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • Royal, Virginie, Université de Montréal, Montreal, Quebec, Canada
  • Nasr, Samih H., Mayo Clinic , Rochester, Minnesota, United States
  • Ecotiere, Laure, CHU Poitiers Néphrologie, Poitiers, France
  • Troyanov, Stephan, Hopital du Sacre-Coeur de Montreal, Town of Mount Royal, Quebec, Canada
  • Alexander, Mariam P., Mayo Clinic , Rochester, Minnesota, United States
  • Leung, Nelson, Mayo Clinic , Rochester, Minnesota, United States
  • Bridoux, Frank, Hôpital Jean Bernard, CHU Poitiers, Poitiers, France
Background

Cast nephropathy (CN) is the main cause of acute kidney injury (AKI) in multiple myeloma (MM). Renal prognosis is poor and chronic renal impairment strongly affects survival. Whether renal biopsy can help in the management of AKI is unclear. The aim of this study was to investigate the prognostic value of renal biopsy findings in CN.

Methods

We retrospectively reviewed renal biopsies from 161 CN patients in a multicenter cohort (9 centers). Histological features, including the extent of cast formation, were independently scored by 2 pathologists. We assessed reproducibility, correlations with clinical presentation and, in patients with 〉3 months follow-up (n=135), associations between biopsy findings, hematologic and renal outcomes.

Results

Interclass Correlation (ICC) for inter-reader concordance was good to excellent (〉0.60) for medullary interstitial inflammation, giant cell reaction around casts, highest and mean cortical and medullary cast numbers. It was moderate (0.40-0.59) for interstitial fibrosis, cortical interstitial inflammation, tubular rupture, interstitial giant cell and Tamm-Horsfall extravasation. We found 46% of kappa CN and 54% of lambda CN. The severity of AKI correlated with higher serum free light chain level (sFLC), ß2-microglobulin, LDH and bone marrow infiltration. The presence of giant cell reaction, highest and mean medullary and cortical number of casts and medullary interstitial inflammation also correlated with a lower initial eGFR. Following therapy, renal response rate was lower with higher age, ß2-microglobulin and baseline sFLC. It was greater with a lower serum creatinine level and greater sFLC reduction. The presence of giant cell reaction, moderate or severe interstitial fibrosis, highest and mean medullary and cortical number of casts and, marginally (p=0.06), medullary interstitial inflammation, also correlated with lower renal recovery rate .

Conclusion

Histologic scoring of CN enables reproducible assessment of morphologic parameters with prognostic significance and may guide the management of MCN.

Participants:
G. Touchard, H. Fatima, F. Rosenblum, P. Sanders, M. Drosou, M. Rabant, C. Cohen, B. Knebelmann, B. Adam, B. Sis, C. Venner, H. Rennke, S. Motwani, R. Manso, K. Soto, A. Barraca, F. Maletta, D. Rocatello, R. Fenoglio, AM. Asuntis, P. Bianco, A. Pani, A. Angioi.

Funding

  • Clinical Revenue Support