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August 8, 2017

Pushing Glass (August 8, 2017)

A 69-year-old man with past medical history of hypertension presents with nephrotic syndrome and 7 gm/day proteinuria. Serological studies are negative for hepatitis B and C. The images are characteristic findings of which of the following:

1. Amyloidosis
2. Fibrillary Glomerulopathy
3. Light chain deposition disease
4. Diabetic nephropathy
5. Fibronectin glomerulopathy

This is a case represents classic findings of fibrillary glomerulopathy. Fibrillary glomerulopathy has been found to be associated with hepatitis C infection, malignancy, dysproteinemia and autoimmune disease (see References below). The deposits in fibrillary glomerulopathy are weakly PAS-positive, silver negative and Congo red negative. By electron microscopy, there are randomly arranged fibrils in the mesangium and glomerular basement membranes. The fibrils are much larger than amyloid fibrils, with an average diameter of 18-20 nm (range 10-30 nm). Amyloid deposits are typically Congo red positive and usually 7-10 nm in diameter. In light chain deposition disease, there are powdery electron-dense deposits in the tubular and glomerular basement membranes representing kappa or lambda restricted light chains. Diabetic nodules are typically, strongly PAS and silver positive, Congo red negative and predominantly composed of basement membrane material that is not electron dense. Fibronectin deposits stain red with trichrome, are electron dense and stain positive for fibronectin.
Reference: GS Markowitz et al. Hepatitis C Viral Infection Is Associated With Fibrillary Glomerulonephritis and Immunotactoid Glomerulopathy J Am Soc Nephrol 9 (12), 2244-2252. 1998.
Nasr SH et al, Fibrillary glomerulonephritis: a report of 66 cases from a single institution. Clin J Am Soc Nephrol. 6(4): 775-784, 2011.