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membranoproliferative glomerulonephritis
Wednesday 12 May 2004
Definition : Membranoproliferative glomerulonephritis or MPGN is a type of glomerulonephritis (GN) caused by IgG deposits in the kidney glomerular mesangium and basement membrane (GBM), activating complement and damaging the glomeruli.
The GBM is rebuilt on top of the deposits, causing a "tram-tracking" appearance under the microscope. MPGN accounts for approximately 4% of primary renal causes of nephrotic syndrome in children and 7% in adults.
Examples
cryoglobuliemia-asscociated glomerulonephritis
- https://twitter.com/AnneMillsMD/status/806279450371510272
- https://twitter.com/BethBraunhut/status/856577188140916736
Synopsis
diffuse lobular simplification of glomeruli
extensive endocapillary proliferation
mesangial hypercellularity (increased number of cells in mesangium - mesangial cells)
increased glomerular basal membrane thickness
extensive double contours of the glomerular basement membranes
- mesangial interposition
- new basement membrane formation
- response to subendothelial immune complex deposits
- PAS positive and globular-to-sausage shaped deposits
Immunofluorescence
- IgG deposits
- segmental, coarsely granular-to-globular IgG deposits
- elongated capillary wall IgG deposits
- subendothelial, segmental, irregular IgG capillary wall deposits
- smooth outer contour
- molding against the glomerular basement membrane (type 1)
- smooth outer contour
Etiology
immune complex-mediated membranoproliferative glomerulonephritis
- chronic infections
Types
membranoproliferative glomerulonephritis type 1
membranoproliferative glomerulonephritis type 2
Ultrastructure
multiple, large subendothelial deposits
multiple, small-to-medium subendothelial deposits
marked endocapillary proliferation (proliferating endothelial and mesangial cells)
- occlusion of the capillary lumen
large subendothelial dense immune complex-type deposits
- subendothelial deposit between the glomerular basement membrane and mesangial cell
mesangial dense immune complex-type deposits
mesangial interposition without evident deposits
- "tram-track" image (double contour of the basement membrane)
Atlas of renal pathology by Agnes Fogo