Diagnosing a Challenging Nephrology Case (Video)

Case study shows value of looking for ‘masked’ evidence

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.

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Figures 1-3 show some of the findings from the renal biopsy.

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Figure 1. A glomerulus showing prominent membranoproliferative features with duplication of glomerular basement membranes and subendothelial deposits (Jones methenamine silver stain, 400x magnification).

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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.

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Figure 3. Electron microscopy (2900x magnification) revealing highly electron-dense subendothelial deposits accompanied by macrophage infiltration.

 

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Dr. Herlitz is Cleveland Clinic’s Director of Medical Kidney Pathology.