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Abstract: PO1750

A Case of "Immunofluorescence-Negative" Lambda Light Chain Deposition Disease

Session Information

Category: Trainee Case Report

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Buch, Kunal B., Emory University, Atlanta, Georgia, United States
  • Vaidya, Satyanarayana R., Emory University, Atlanta, Georgia, United States
  • Caberto, Sheryl C., Emory University, Atlanta, Georgia, United States
  • Farris, Alton Brad, Emory University, Atlanta, Georgia, United States
Introduction

Light chain deposition disease (LCDD) is the most common form of monoclonal immunoglobulin deposition disease (MIDD). Pathologically, glomeruli develop nodular expansion of mesangial regions and deposits of monoclonal light chain (LC) positive, electron dense deposits within glomerular and tubular Basement menbrane. (1,2) The majority of monoclonal LC in LCDD are of kappa type. (3) We report a case of lambda LCDD with negative immunofluorescence microscopy (IF), but with characteristic granular, basement membrane, electron dense deposits on ultrastructural examination.

Case Description

A 42-year-old Caucasian female with no PMHx, no NSAID, Chinese herbal or PPI use presented with fatigue, malaise and dark urine for 2 weeks. She had a normal BP and no edema. Labs: Scr was 2.4 mg/dL with unknown baseline levels, BUN 26 mg/dL, Hb level 9.0 gm/dL with MCV of 90 fl, with a negative autoimmune panel. Urine microscopy showed 10 RBC/HPF and 24-hour protein excretion was 460 mg. SPEP and immunofixation detected a Lambda LC monoclonal paraprotein. Serum free Lamba LC level was 1044 mg/L with free kappa/lambda LC levels ratio of 0.03.

A kidney biopsy revealed nodular expansion of glomerular mesangial regions, modest amount of IFTA. RBCs and red cell casts were present in tubules. Direct IF microscopy with FITC-conj. anti-human IgG, IgM and IgA heavy chains and Kappa/lambda light chains was negative with testing performed in duplicate. Ultrastructural examination revealed powdery, granular electron dense deposits diffusely along tubular and glomerular basement membranes with focal areas of podocyte foot process effacement. Bone marrow biopsy revealed plasma cell neoplasm.

Discussion

Our patient underwent autologous SCT after pretreatment with Melphalan. Renal function has been stable at stage III CKD. She never developed HTN or significant proteinuria, which usually are some of the presenting features of LCDD. She had lambda LC paraproteinemia, which is a more common feature of heavy chain deposition disease than LCDD. Direct IF microscopy was negative, which could be due to abnormal LCs being truncated in the tissue deposits, and commercially available, FITC-conj., anti-human Abs might not have been able to detect them. (4) This case emphasizes the fact that negative staining by routine, direct IF microscopy methods does not exclude the presence of MIDD.