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Kidney non-tumor

Primary glomerular diseases

Minimal change glomerulopathy

Reviewers: Nikhil Sangle, M.D. (see Reviewers page)
Revised: 4 September 2012, 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

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

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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