Kidney nontumor
Primary glomerular diseases
Focal segmental glomerulosclerosis (FSGS), collapsing variant

Author: Amanda Breitbarth, M.D. (see Authors page)
Senior Author: Nicole K. Andeen, M.D.
Editor-in-Chief Review: Debra Zynger, M.D.

Revised: 28 November 2018, last major update October 2018

Copyright: (c) 2018, PathologyOutlines.com, Inc.

PubMed Search: Focal segmental glomerulosclerosis collapsing variant

Cite this page: Breitbarth A, Andeen NK. Focal segmental glomerulosclerosis (FSGS), collapsing variant. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/kidneyfsgscollapsing.html. Accessed December 12th, 2018.
Definition / general
  • Morphologic variant of focal segmental glomerulosclerosis (FSGS) characterized by capillary loop collapse and prominence of overlying epithelial cells (Semin Nephrol 2003;23:209)
Essential features
  • At least 1 glomerulus with capillary loop collapse and prominence of overlying podocytes or parietal epithelial cells
  • Worse prognosis than other variants of focal segmental glomerulosclerosis; supersedes other variants if others present in biopsy
  • May be associated with viruses, genetics, drugs, vascular injury and autoimmune diseases
Terminology
  • Collapsing glomerulopathy (CG), collapsing focal segmental glomerulosclerosis (FSGS), FSGS collapsing variant
  • Early descriptions as a component of HIV associated nephropathy
ICD coding
Epidemiology
  • APOL1 high risk alleles common in individuals with African ancestry are associated with increased rates of kidney injury including collapsing focal segmental glomerulosclerosis (Kidney Int 2015;87:332)
Pathophysiology
  • No single pathogenic trigger has been identified
Etiology
Clinical features
  • High incidence of nephrotic syndrome
  • Renal insufficiency
Diagnostic criteria
  • Renal biopsy with at least 1 glomerulus with collapse and overlying epithelial cell hypertrophy or hyperplasia (Columbia classification, Am J Kidney Dis 2004;43:368)
Laboratory
Prognostic factors
Case reports
Treatment
  • Treatment of underlying etiology, if identifiable
  • In patients with HIV, highly active antiretroviral therapy (HAART) is the first line treatment and reduces rates of progression to end stage renal disease (J Am Soc Nephrol 2005;16:2412)
  • In virus negative patients, steroid therapy and other immunosuppression is frequently used, although often refractory (J Am Soc Nephrol 2006;17:2854)
Microscopic (histologic) description
  • At least 1 glomerulus with segmental collapse of the tuft, obliteration of the capillary loops and overlying podocyte or parietal cell hypertrophy or hyperplasia (Am J Kidney Dis 2004;43:368)
  • May appear as pseudocrescents filling Bowman space
  • Podocytes frequently form a radial corona around the glomerular tuft and have protein resorption droplets
  • Lacks necrosis
  • Particularly in HIV associated collapsing focal segmental glomerulosclerosis, may have significant chronic tubulointerstitial scarring and tubular microcysts
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Nicole K. Andeen, M.D.

Collapse of the glomerular tuft and prominence of the overlying epithelial cells, Jones stain

PAS

Trichrome



Images hosted on other servers:

Collapsed glomerulus

With sickle cell disease

Various images

Positive stains
Negative stains
Immunofluorescence description
  • Negative or nonspecific
    • Collapsed segments with nonspecific IgM or C3 staining
    • Visceral epithelial resorption droplets: IgG, IgA, light chains or albumin
    • Tubular resorption droplets: IgG, IgA, light chains or albumin
Electron microscopy description
  • Podocyte foot process effacement
  • Endothelial tubuloreticular inclusions may be present in high interferon states, including HIV associated, lupus associated and interferon mediated collapsing glomerulopathy
Electron microscopy images

Images hosted on PathOut server:

Contributed by Nicole K. Andeen, M.D.

Podocyte foot process effacement

Differential diagnosis
  • Focal segmental glomerulosclerosis (FSGS), cellular variant:
    • Cellular variant has segmental to global endocapillary hypercellularity (occlusion of capillary loops due to influx of leukocytes, foam cells or endothelial cell swelling) and prominence of overlying epithelial cells in Bowman space
    • Lacks collapse of glomerular tuft
  • Crescentic glomerulonephritis:
    • Segmental breaks in glomerular basement membrane and necrosis, influx of leukocytes in glomeruli and layered crescent orientation of cells in Bowman space
    • May occasionally be difficult to distinguish in isolation; perform additional levels and evaluate surrounding parenchyma and clinical scenario
  • Focal segmental glomerulosclerosis (FSGS), NOS:
    • Lacks collapse of glomerular tuft
Board review question #1
If present on kidney biopsy, which variant of focal segmental glomerulosclerosis (FSGS) has a significantly poorer prognosis and supersedes the presence of others (if other variants are present in the same biopsy) in the FSGS classification?

  1. Cellular variant
  2. Collapsing variant
  3. Hilar variant
  4. Tip variant
Board review answer #1
B. Collapsing variant
Board review question #2
A patient has a kidney biopsy for nephrotic syndrome. What does this image represent?



  1. Amyloidosis
  2. Cellular crescent
  3. Collapsing focal segmental glomerulosclerosis
  4. Minimal change disease
Board review answer #2
C. Collapsing focal segmental glomerulosclerosis

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