Kidney nontumor
Primary glomerular diseases
Minimal change glomerulopathy


Topic Completed: 8 January 2019

Revised: 8 April 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Minimal change glomerulopathy[TIAB]

Ana Belén Larqué, M.D., Ph.D.
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Cite this page: Larqué AB. Minimal change glomerulopathy. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneyminchange.html. Accessed July 18th, 2019.
Definition / general
  • Idiopathic glomerular disease that causes nephrotic syndrome
  • Little or no light or immunofluorescent microscopic abnormalities
  • Diffuse foot process effacement on electron microscopy (BMC Nephrol 2018;19:207)
Essential features
  • Renal glomeruli appear normal by light and immunofluorescence microscopy
  • Extensive effacement of podocyte foot processes by electron microscopy (hallmark)
  • Highly selective proteinuria, mainly albuminuria
  • Responds well to treatment with corticosteroids (90 - 95%)
Terminology
  • Also called minimal change disease, idiopathic nephrotic syndrome, nil disease, lipoid nephrosis and foot process disease
ICD coding
  • ICD-10: N00 - N08 - Glomerular diseases
  • ICD-10: N04.9 - Nephrotic syndrome with unspecified morphologic changes
Epidemiology
  • Most common type of nephrotic syndrome in children: 70 - 90%; in adults: 11 - 16%
  • Peak incidence in children: 2 - 3 years; in adults: 80 - 91 years
  • In children, M:F = 2:1; in adults, M = F
  • More common in Caucasians and Asians than African-Americans (Clin J Am Soc Nephrol 2007;2:445)
Sites
  • Glomerular disease
Pathophysiology
Etiology
Diagrams / tables

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Lipoid nephrosis

Clinical features
  • Nephrotic syndrome
  • Proteinuria selective for albumin, causing hypoalbuminemia leading to severe edema
  • Lipiduria, hypercholesterolemia but usually no hypertension, no hematuria and no azotemia
  • Microhematuria (10 - 30%)
  • Can present as acute renal insufficiency in adults (Clin J Am Soc Nephrol 2017;12:332)
Diagnosis
  • Nephrotic syndrome with little or no light or immunofluorescent microscopic abnormalities
  • Diffuse foot process effacement on electron microscopy
Laboratory
Prognostic factors
  • Rarely, if ever, leads to end stage renal disease without development of focal segmental glomerulosclerosis
  • Adults with minimal change disease and acute renal failure also usually fully recover (Medicine (Baltimore) 2014;93:e300)
  • Relapses common and often lead to steroid dependence
Case reports
Treatment
Gross description
  • Enlarged, waxy yellow cortex due to lipid accumulation in proximal tubules
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Ana Belén Larqué, M.D., Ph.D.

Aggregates of lipid laden macrophages



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Relatively normal
appearing glomeruli
and lipoid nephrosis

Immunofluorescence description
  • Negative except for variable focal IgM ± C3
Electron microscopy description
  • Extensive foot process effacement (foot processes retract into cell bodies, not actually fusion)
  • Microvillous transformation of epithelial cells, cyst formation
Electron microscopy images

Contributed by Ana Belén Larqué, M.D., Ph.D.

Hypertrophic podocytes



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Foot process effacement

Molecular / cytogenetics description
  • Rarely familial (Semin Nephrol 2003;23:141, Hum Mol Genet 1995;4:2155, J Am Soc Nephrol 2002;13:388)
    • Histologic findings of focal segmental glomerulosclerosis or more rarely minimal change glomerulopathy are a part of the autosomal recessive steroid resistant nephrotic syndrome
    • Mutations in NPHS2 have been detected in both familial and sporadic steroid resistant nephrotic syndrome
    • NPHS2 gene, formerly SRN1, encodes podocin, a protein that is almost exclusively expressed in glomerular podocytes
Sample pathology report
  • Left kidney, biopsy:
    • Minimal change glomerulopathy
  • Adequacy: adequate (cortex 85%, medulla 15%)
  • Microscopic description: 19 glomeruli showed normal size and cellularity. There is no interstitial inflammation and no significant interstitial fibrosis or tubular atrophy. Tubules are preserved, without significant evidence of injury. Small arteries and arterioles show minimal interstitial fibrosis. There is no vasculitis.
  • Immunofluorescence microscopy:
    • Number of glomeruli: 4
    • There were no deposits of IgA, IgM, IgG, C3, C1q or fibrin
  • Electron microscopy: Extensive effacement of the foot processes covering over 80% of the glomerular capillary surface. The glomerular basement membrane showed normal thickness and a generally smooth contour. No electron dense deposits were noted on the glomerular capillary basement membranes or mesangial areas. The mesangial area contained normal amounts of matrix and cells.
Differential diagnosis
  • Focal segmental glomerulosclerosis:
    • Segmental hyalinosis or synechiae to Bowman capsule, interstitial fibrosis or tubular atrophy
    • Cases with unsampled glomerulosclerosis may be misdiagnosed as minimal change disease
  • Mesangial glomerulonephritis:
    • Early mesangial glomerulonephritis can be indistinguishable on light microscopy
    • Positive immunofluorescence and electron dense subepithelial deposits on electron microscopy
  • Chyluria:
    • Normal podocytes with heavy proteinuria
  • IgA nephropathy:
    • Minimal change disease could be superimposed on IgA nephropathy
Board review question #1
Which of the following is true about minimal change glomerulopathy?

  1. Interstitial inflammation and fibrosis are usually absent
  2. It is the most common type of nephrotic syndrome in adults
  3. Monoclonal antibody therapy should be the first line therapy
  4. Pretreatment biopsy is always done
Board review answer #1
A. Interstitial inflammation and fibrosis are usually absent

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Board review question #2
Which of the following signs and symptoms is common in minimal change disease?

  1. Azotemia
  2. Hypertension
  3. Macrohematuria
  4. Selective proteinuria
Board review answer #2
D. Selective proteinuria

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Board review question #3
Which of the following renal lesions is most likely to be present in minimal change disease?

Missing Image

  1. Acute tubular necrosis
  2. Glomerular crescent formation
  3. Mesangial immune complex deposition
  4. Podocyte foot process effacement
Board review answer #3
D. Podocyte foot process effacement

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