By Leal Herlitz, MD
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A renal biopsy was performed on a 74-year-old man with history of diabetes and hypertension. He initially presented in the emergency department with shortness of breath and was found to have acute kidney injury with a serum creatinine of 2.9 mg/dL.
Urinary sediment was active, with numerous red blood cells and 10-25 white blood cells per high power field. A 24-hour urine protein collection showed 4.74 grams of proteinuria.
Serologic workup showed positive antinuclear antibodies (1:80), complement component 3 (C3) of 54 (normal 68-260), complement component 4 (C4) of 27 (normal 12-46) and negative antineutrophil cytoplasmic antibodies, anti-glomerular basement membrane and hepatitis serologies. Serum protein electrophoresis and urine protein electrophoresis showed a monoclonal spike consisting of kappa light chains without an accompanying heavy chain.
What was the final diagnosis? For a review of the case with discussion, watch the video presentation.
Figures 1-3 show some of the findings from the renal biopsy.
Figure 1. A glomerulus showing prominent membranoproliferative features with duplication of glomerular basement membranes and subendothelial deposits (Jones methenamine silver stain, 400x magnification).
Figure 2. Direct immunofluorescence staining for C3 performed by standard techniques on snap-frozen tissue (400x magnification). Staining for immunoglobulin G, immunoglobulin M, immunoglobulin A, C1q, kappa and lambda was negative.
Figure 3. Electron microscopy (2900x magnification) revealing highly electron-dense subendothelial deposits accompanied by macrophage infiltration.
Dr. Herlitz is Cleveland Clinic’s Director of Medical Kidney Pathology.