Abstract: PUB020
Lambda Light-Chain Myeloma Presenting with Acute Kidney Failure and Minimal Bone Involvement
Session Information
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Bai, Sadhna, LSU Health Shreveport, Shreveport, Louisiana, United States
- Kumar, Anand, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
- Kumar, Ravi, Lifecare Hospital Musaffah, Abu Dhabi, United Arab Emirates
- Sequeira, Adrian P., LSU Health Shreveport, Shreveport, Louisiana, United States
Introduction
Light Chain Multiple Myeloma (LCMM) is a distinct subtype of multiple myeloma characterized by the exclusive production of monoclonal light chains (kappa or lambda) without intact immunoglobulin. Unlike other subtypes, LCMM is characterized by an absence of M-spike on serum protein electrophoresis, necessitating the use of serum free light chain assays for diagnosis. LCMM accounts for 15–20% of myeloma cases and is often more aggressive, with a higher risk of renal involvement due to light chain–induced tubular injury and cast nephropathy.
Case Description
A 68-year-old AA male with a history of HTN, prostate cancer (in remission), TURP, and NPH presented with acute renal failure, vomiting, constipation, and bilateral big toe pain. He denied any back or bone pain. The physical exam was unremarkable. Labs revealed severe renal dysfunction (Cr 24.6 mg/dL, B/L 1.5 mg/dL), K+ 7.1, BUN 148, metabolic acidosis (pH 10.3), anemia (Hb 7.4), hyperuricemia (16.3 mg/dL), and Ca+ of 9.9. UA showed hematuria and proteinuria; He was started on dialysis.
Further workup with protein electrophoresis revealed markedly elevated serum free light chain kappa 10.5 mg/L, free light chain lambda 1073 mg/L, and free light chain ratio of 0.0098.
Autoimmune and infectious workup was negative. Bone marrow biopsy showed 55% cellularity with CD138+, CD56+, CD117+ plasma cells, and lambda light chain restriction, confirming light chain myeloma. PET scan showed minimal bone involvement, limited to L5.
Discussion
This case illustrates the diagnostic challenge of LCMM, which often presents with minimal or absent M spike, complicating detection. Markedly elevated lambda free light chains and an atypical M spike indicated aggressive disease with high renal risk. Free light chain assays are essential, as patients may progress to ESRD from light chain nephropathy despite treatment. Though started on CyBorD and discharged stable, the patient eventually developed ESRD—a common outcome in LCMM.