Light-Chain–Mediated Acute Tubular Interstitial Nephritis: A Poorly Recognized Pattern of Renal Disease in Patients With Plasma Cell Dyscrasia

Abstract

Abstract Context.—Acute renal failure may be the first clinical presentation in patients with plasma cell dyscrasia. Recognition of the unusual interstitial inflammatory lesion associated with monoclonal light chains and renal failure described herein is important to guide clinicians in requesting appropriate tests to confirm plasma cell dyscrasia and providing adequate treatment. Objective.—To describe an unusual pattern of tubular interstitial nephritis in patients with underlying plasma cell dyscrasia characterized by an interstitial inflammatory reaction associated with deposition of light chains along tubular basement membranes. Design.—Eight cases of light-chain–mediated acute tubular interstitial nephritis were identified from the archives of 4296 kidney biopsy specimens. In all cases, routine light microscopic examination, direct immunofluorescence, and electron microscopic examination were performed. Ultrastructural immunogold labeling was performed in specimens with inconclusive findings and in specimens from patients with no clinical history of plasma cell dyscrasia. Results.—All patients presented with acute renal failure. Light microscopy revealed acute tubular interstitial nephritis. In some of the cases, direct immunofluorescence and electron microscopy failed to show definitive evidence of light-chain deposition along tubular basement membranes. Ultrastructural immunogold labeling aided the demonstration of monotypical light chains along some tubular basement membranes. No light chains were present in other renal compartments. Conclusions.—Accumulation of light chains along tubular basement membranes may induce an interstitial process that mimics acute tubular interstitial nephritis. Recognition of this unusual pattern of renal disease in patients with plasma cell dyscrasia requires ancillary diagnostic techniques.