Long‐term renal survival of γ3‐heavy‐chain deposition disease complicated by heart failure: A case report.

Key Clinical Message: Heavy‐chain deposition disease (HCDD), a rare monoclonal immunoglobulin deposition disease, involves truncated heavy‐chain deposition in kidneys. Limited long‐term data exist. We report a case of renal and cardiac failure with favorable outcomes post bortezomib‐based therapy. Stable renal function observed over 4 years suggests efficacy in HCDD with multisystem involvement. Heavy‐chain deposition disease (HCDD) is an extremely rare form of monoclonal immunoglobulin deposition disease (MIDD) that involves the deposition of truncated immunoglobulin heavy chains in the kidneys. Only a few cases of HCDD with a favorable long‐term renal prognosis have been reported, resulting in limited long‐term follow‐up data for this patient population. In this report, we present the case of a 52‐year‐old patient with nephrotic syndrome who experienced renal failure and cardiac failure. Renal biopsy confirmed the presence of γ3‐HCDD and monoclonal Immunoglobulin G (IgG)κ in the serum. The patient exhibited low voltage on electrocardiogram (ECG) and unexplained left ventricular hypertrophy on cardiac ultrasound. The patient underwent eight cycles of bortezomib‐based chemotherapy, which led to hematological remission. After 4 years of follow‐up, the patient's renal function remained stable, with serum creatinine levels ranging from 0.7 to 0.9 mg/dL and proteinuria of 0.3–0.5 g/24 h. Our findings suggest that bortezomib‐based chemotherapy is equally effective in HCDD patients with combined multisystem damage. [ABSTRACT FROM AUTHOR]