Nephrotic syndrome in a 51-year-old woman with light chain deposition disease.

Light chain deposition disease (LCDD), an uncommon monoclonal renal disease linked to plasma cell neoplasm, can cause nephrotic syndrome and renal failure. Early diagnosis via renal biopsy is crucial. We describe a 51-year-old woman patient with multiple myeloma complicated with light chain nephropathy who presented with edema, proteinuria, and hypoalbuminemia. The serum-free kappa/lambda ratio was elevated. Renal biopsy revealed kappa light chain deposits, and electron microscopy revealed powdery electron-dense deposits, which confirmed the diagnosis. Chemotherapy and autologous stem cell transplantation reduced proteinuria and improved renal function. LCDD requires a prompt renal biopsy for diagnosis. Proteasome inhibitor-based therapies combined with stem cell transplantation significantly improve outcomes, highlighting the importance of early intervention in patients with renal impairment.