Light-chain deposition disease (LCDD) is characterized by extracellular tissue deposition of non-amyloid monoclonal immunoglobulin light chains (predominantly kappa light chains) in various organs including kidneys, heart, and liver. It is a rare cause of renal insufficiency. In two-thirds of cases it is associated with multiple myeloma, while in the remainder their monoclonal B cell proliferation does not meet the criteria for that diagnosis.Renal involvement occurs almost invariably and dominates the clinical course of the disease: greater than 90% of patients with LCDD have renal functional impairment; acute or rapidly progressive kidney failure usually develops over a period of months. Nephrotic-range proteinuria is present in 40–50% of patients while approximately 20% of patients develop nephrotic syndrome. Arterial hypertension and microscopic haematuria can be present. Extrarenal symptoms are related to affected organs with cardiomyopathy, cachexia, haemorrhages, infections, and MM progression as main causes of death.The diagnosis of LCDD is often delayed and whilst bone marrow examination will often identify associated MM, renal biopsy frequently provides the final diagnostic proof. Abnormal light chains can be detected and quantified by serum or urine protein electrophoresis and immunofixation. Quantification of urine and serum free kappa/lambda light chains has proven a useful screening tool and might also plays a role in therapeutic monitoring.Treatment consists of chemotherapy directed against the monoclonal immunoglobulin-producing plasma cells.
Kappa light chain-associated Fanconi's syndrome: molecular analysis of monoclonal immunoglobulin light chains from patients with and without intracellular crystals
