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Abstract: SA-PO169

Monoclonal Gammopathy Manifested as Renal Interstitial Amyloidosis

Session Information

Category: Onconephrology

  • 1700 Onconephrology

Authors

  • Qasim, Muhammad, University of Kentucky College of Medicine, Lexington, Kentucky, United States
  • Mustafa, Kanza, Yusra Medical and Dental College, Islamabad, Pakistan
  • Finke, Ann R., University of Kentucky College of Medicine, Lexington, Kentucky, United States
  • Cornea, Virgilius, University of Kentucky College of Medicine, Lexington, Kentucky, United States
  • Ayach, Taha, University of Kentucky College of Medicine, Lexington, Kentucky, United States
Introduction

Amyloidosis is a disorder caused by deposition of insoluble misfolding proteins as fibrils leading to organ dysfunction. Incidence of AL Amyloidosis is 9 cases per million. Monoclonal gammopathy manifested as renal interstitial amyloidosis is a rare disorder.

Case Description

54 yo F with history of hypothyroidism, covid 19 presents to primary care provider (PCP) with fatigue. Cr was noted to be 1.28 mg/dl, eGFR 50ml/min. Urinalysis was bland, and urine protein to creatinine ratio was 0.2 g/g. Renal U/S: Normal. SPEP: Normal. Serum free light chains (LC) K 249.23 mg/L[3.3-19.4], λ 10.90 mg/L[5.71-26.3], elevated K/λ LC ratio of 22.87[0.26-1.65]. Bone marrow biopsy(BMBx): plasma cell dyscrasia,15% of the population of K-restricted plasma cells, negative Congo Red stain. Skeletal survey: negative. Renal Biopsy: proximal tubulopathy, monoclonal kappa light chain related and Interstitial renal amyloid deposition.

Discussion

Isolated K related monoclonal gammopathy manifested as renal interstitial amyloid is a rare disease entity scarcely reported in literature. We report a case of this patient with mild symptoms and minimal serum Cr elevation, no significant proteinuria with elevated K/λ LC ratio. BMBx: K-related plasma cell abnormality. Renal biopsy: K LC proximal tubulopathy along with interstitial amyloid deposits. Treated with lenalidomide, bortezomib, dexamethasone[6 cycles]. Achieved remission confirmed on BMBx. Had autologous hematopoietic stem cell transplant. Remains in remission on lenalidomide maintenance dose 20 months post auto-HCL. Renal function stable with serum Cr ~ 1-1.2 mg/dL with bland urine.

A&B- H&E.Proximal Tubulopathy,Acute Tubular Damage. C&D-Amyloid interstitial deposits- Congo Red. D:Apple-green; Polarized Light. E-H:(IF) E-Tubules,2+ cytoplasmic staining after pronase digestion for K-LC. F-Tubules, no cytoplasmic staining after pronase digestion for λ-LC. G&H, interstitial staining for Kappa(G) and lambda(H) after pronase digestion. I-J:EM, enlarged atypical shaped lysosomes (J) and IC rhomboid and needle shaped crystals (I-L).