Kidney non-tumor - Minimal change glomerulopathy

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Kidney non-tumor

Primary glomerular diseases

Minimal change glomerulopathy

Reviewers: Nikhil Sangle, M.D. (see Reviewers page)
Revised: 24 February 2014, last major update September 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Also called minimal change disease, nil disease, lipoid nephrosis and foot process disease
● Causes 80% of cases of nephrotic syndrome in children (usually ages 2-6), 20% in adults

Pathophysiology
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● Extensive foot process "fusion" appears to be due to epithelial injury with loss of glomerular anionic charge
● Overproduction of angiopoietin-like 4 (ANGPTL4) in podocytes causes it to bind to glomerular basement membrane, leading to selective proteinuria, diffuse effacement of foot processes and loss of glomerular basement membrane charge (Am J Kidney Dis 2012;59:284, Nat Med 2011;17:117); due in part to sialic acid residue deficency in ANGPTL4 (oral supplementation with sialic acid precursor N-acetyl-d-mannosamine improves sialylation of podocyte-secreted ANGPTL4 and significantly decreases proteinuria)
● "Fusion" is actually simplification of epithelial architecture with flattening, retraction and swelling of foot processes; also seen in membranous glomerulopathy and diabetes; reverts to normal with remission

Lipoid nephrosis

Clinical features
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● Nephrotic syndrome, proteinuria selective for albumin, causing hypoalbuminemia leading to severe edema
● Elevated serum cholesterol, but with minimal microscopic glomerular alterations and usually no hypertension, no hematuria and no azotemia
● Note: minimal change disease, diffuse mesangial hypercellularity and focal and segmental glomerulosclerosis may be a continuum of the same disease
● Associated with respiratory infections, immunizations, lead or mercury ingestion, allergies, acute interstitial nephritis and Hodgkin’s lymphoma; in elderly, associated with NSAIDs

Case reports
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● Intravascular B cell lymphoma of kidney associated with minimal change disease (Hum Pathol 1989;20:263)

Treatment
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● 90% of children respond to steroids initially (foot processes return to normal), may require immunosuppression, < 5% develop renal failure after 25 years
● Some children become steroid dependent / resistant, but this usually resolves at puberty
● Older adults with hypertension and severe proteinuria have a higher risk of reversible renal failure
● Rituximab may be effective in adults (Clin Nephrol 2011;76:151)
● May develop nephrocalcinosis due to hypercalciuria from chronic furosemide use (Hum Pathol 2000;31:1363)

Gross images
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Lipoid nephrosis

Micro description
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● Normal glomeruli, tubules have lipid droplets due to reabsorption of lipoproteins that leak from glomeruli ("lipoid nephrosis")

Micro images
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Relatively normal appearing glomeruli and lipoid nephrosis

Glomerulus with normal size and cellularity

Normal glomeruli and intact parenchyma

Normal glomerulus on PAS

Normal glomerulus on Silver stain

Unremarkable glomerulus on Silver stain

Immunofluorescence
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● Generally negative
● May show weak non-specific IgM in mesangial distribution, but no deposits in GBM
● Albumin in proximal tubular epithelial cells

Immunofluorescence images
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Only background staining by immunofluorescence

Electron microscopy description
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● Extensive foot process effacement (foot processes retract into cell bodies, not actually fusion)
● Microvillous transformation of epithelial cells, cyst formation

Electron microscopy images
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Foot process effacement

Complete foot process effacement

Differential diagnosis
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● Focal and segmental glomerulosclerosis: tubular atrophy and interstitial scarring; global glomerular sclerosis may be present in minimal change disease if there is underlying arterionephrosclerosis; minimal change disease may also be associated / superimposed on other conditions such as IgA nephropathy

End of Kidney non-tumor > Primary glomerular diseases > Minimal change glomerulopathy

Ref Updated: 5/29/12

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