Primary Cardiac and Renal Amyloidosis with Nephrotic Syndrome in a Patient with a Remote History of Partial Nephrectomy for Renal Cell Carcinoma.

BACKGROUND: Primary AL amyloidosis is a rare systemic disorder caused by deposition of misfolded immunoglobulin light chains, leading to multi-organ dysfunction. Renal cell carcinoma (RCC) is common, with an age-adjusted incidence of 16.4 per 100,000 persons per year in the US (2017-2021). Post-partial nephrectomy, mild proteinuria may occur, but progressive glomerular disease such as AL amyloidosis years later is rare. CASE PRESENTATION: A 73-year-old man with ulcerative colitis, type 2 diabetes, RCC post right partial nephrectomy (10 years prior), and prostate cancer post-prostatectomy (4 years prior) presented with fatigue and bilateral leg edema. Laboratory evaluation revealed acute kidney injury with nephrotic-range proteinuria, hypoalbuminemia, and elevated cardiac biomarkers. Serum and urine protein electrophoresis revealed IgA kappa monoclonal protein. Renal biopsy confirmed AL amyloidosis, and endomyocardial biopsy confirmed cardiac involvement. Bone marrow biopsy showed 10% clonal plasma cells without myeloma-defining events, excluding multiple myeloma. The patient received Dara-CyBorD chemotherapy and hemodialysis. Despite therapy, renal function remained dialysis-dependent, and cardiac and hematologic responses plateaued after one year. DISCUSSION: This case highlights the diagnostic challenges and multi-organ involvement of AL amyloidosis in a patient with prior malignancy. RCC and AL amyloidosis coexist independently, and early recognition is critical for management. CONCLUSION: AL amyloidosis can occur in patients with a remote history of RCC. Clinicians should maintain high suspicion in patients with nephrotic-range proteinuria and cardiac involvement. Early recognition, staging, and therapy may improve outcomes, although irreversible organ damage may limit recovery.