Fibrillary Glomerulonephritis

Abstract

The AJKD Atlas of Renal Pathology presents a compilation of figures on a specific pathologic entity. You may download the figures to create your own personal, non-commercial library of images or to create slides for teaching purposes. The AJKD Atlas of Renal Pathology presents a compilation of figures on a specific pathologic entity. You may download the figures to create your own personal, non-commercial library of images or to create slides for teaching purposes. Fig 2Fibrillary glomerulonephritis may have varying degrees of mesangial proliferation or membranoproliferative pattern by light microscopy. In this case, there was moderate mesangial proliferation and occasional basement membrane splitting. Additional studies confirmed the diagnosis of fibrillary glomerulonephritis with typical electron microscopy appearance, negative Congo red stain, and IgG staining by immunofluorescence (Jones silver stain; original magnification ×400). See other figures.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 3In approximately one third of cases seen in our series of fibrillary glomerulonephritis, crescents were present, as in this case. In some of these, confluent deposits caused immunofluorescence to have a pseudolinear appearance, which could give rise to diagnostic confusion until electron microscopy is examined (Jones silver stain; original magnification ×200).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 4Immunofluorescence studies in fibrillary glomerulonephritis are striking and characteristic with smudgy positivity in mesangial and capillary loop areas. The mesangial staining most commonly is more extensive than the capillary loop staining, and the typical smudginess allows suspicion of fibrillary glomerulonephritis. The most common staining is IgG, with IgG4 subtype typically being most prominent (anti-IgG immunofluorescence; original magnification ×400).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 5The diagnosis of fibrillary glomerulonephritis is ultimately made by electron microscopy, which shows randomly arranged fibrils in mesangial and capillary loop areas with an intramembranous, subepithelial, and/or subendothelial location. Negative Congo red stains are necessary to specifically exclude the possibility of amyloid (transmission electron microscopy; original magnification ×25,625).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 6Higher power shows randomly oriented fibrils in the mesangium and glomerular basement membrane in fibrillary glomerulonephritis. These fibrils tend to be slightly larger than those in amyloid, although there is some overlap so that fibril size alone cannot be used to definitively distinguish this from amyloid. A negative Congo red stain should be done to rule out amyloid deposits (transmission electron microscopy; original magnification ×51,250).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 7Distinct subepithelial localization of fibrillary deposits in a case of fibrillary glomerulonephritis. In this case, immunofluorescence and light microscopic studies gave the impression of a membranous glomerulonephritis, illustrating the utility and need for electron microscopy to definitively evaluate renal biopsies. The fibrils are randomly oriented and somewhat larger than in amyloid, 12 to 15 nm, although there is some overlap so that size alone cannot be used to definitively distinguish this from amyloid deposits (transmission electron microscopy; original magnification ×62,000).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 8High-power view of fibrils in fibrillary glomerulonephritis, illustrating slightly coarser diameter than in amyloid. The fibrils are randomly arranged in the loose background. A negative Congo red stain is necessary to definitively rule out amyloid deposits, although fibrillary glomerulonephritis can be suspected from the characteristic immunofluorescence microscopy and the slightly larger fibril size (transmission electron microscopy; original magnification ×98,000). See other figures.View Large Image Figure ViewerDownload Hi-res image Download (PPT)