Minimal Light Microscopic Changes

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Renal pathology tutorial for nephrologists

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Minimal Light Microscopic Changes

  1. 1. Minimal LM canges
  2. 2. <ul><li>Minimal Light Microscopic Alterations </li></ul><ul><ul><li>Minimal change disease </li></ul></ul><ul><ul><li>Thin glomerular basement membrane disease (TBMD) </li></ul></ul><ul><ul><li>Lupus nephritis, class I </li></ul></ul><ul><ul><li>Immunoglobulin A (IgA) nephropathy, with no lesion by light microscopy </li></ul></ul>
  3. 3. Minimal Change Disease <ul><li>Histopathology: </li></ul><ul><li>LM usually discloses no significant abnormalities </li></ul><ul><li>GBM- unremarkable thickness and texture </li></ul><ul><li>Mesangium +/- mild expansion </li></ul><ul><li>Podocytes +/- slightly prominent but no proliferative changes (pseudocrescents) </li></ul><ul><li>Proximal tubules may contain prominent protein reabsorption granules </li></ul><ul><li>The interstitium is usually delicate; foamy macrophages may be seen on rare occasions </li></ul><ul><li>Acute interstitial nephritis may be seen in association with drug-induced (particularly NSAID-induced) minimal change disease </li></ul><ul><li>Interstitial fibrosis and tubular atrophy may be seen in elderly patients with comorbid states </li></ul>
  4. 4. <ul><li>Immunofluorescence: </li></ul><ul><li>+/- fine granular reactivity for IgG within the podocyte cytoplasm (dusting). </li></ul><ul><li>No immune deposits present along the peripheral capillary loops or in the mesangium </li></ul><ul><li>Electron microscopy: </li></ul><ul><li>Visceral epithelial cells: Hallmark- diffuse effacement of visceral epithelial cell foot processes in the absence of electron-dense deposits . </li></ul><ul><li>Other degenerative changes of visceral epithelial cells: microvillous degeneration, vacuolization of the cytoplasm, increased number of lysosomes and other cytoplasmic organelles </li></ul><ul><li>GBM: Usually unremarkable </li></ul><ul><li>Glomerular endothelial cells: Usually unremarkable and do not contain tubuloreticular structures </li></ul><ul><li>Mesangium: Normal cell elements and an extracellular matrix without electron-dense deposits </li></ul>
  5. 7. IgA
  6. 9. <ul><li>Histopathology: </li></ul><ul><li>Glomeruli are normal, or they show minimal mesangial expansion </li></ul><ul><li>The glomerular basement membranes are of unremarkable thickness and texture </li></ul><ul><li>The mesangium may be minimally expanded, but is normocellular </li></ul><ul><li>The tubulointerstitium is usually unremarkable </li></ul><ul><li>This form of IgA is quite common and can be detected incidentally on renal biopsy, superimposed to any other renal disease </li></ul>
  7. 10. <ul><li>Immunofluorescence: </li></ul><ul><li>Dominant reactivity for IgA in the mesangium; C3 may be equally or less reactive. There is usually stronger reactivity for lambda than for kappa light chains in the mesangial deposits </li></ul><ul><li>Electron microscopy: </li></ul><ul><li>Visceral epithelial cells: Unremarkable, with well-preserved foot processes </li></ul><ul><li>Glomerular basement membranes: May be thin; there is higher incidence of thin glomerular basement membrane disease in IgA nephropathy than in any other glomerular disease. </li></ul><ul><li>Glomerular endothelial cells: Usually unremarkable and tubuloreticular structures are not seen. </li></ul><ul><li>Mesangium: Shows normal cell elements and an extracellular matrix with scattered small fine granular electron-dense deposits </li></ul>
  8. 12. Class I lupus nephritis <ul><li>Histopathology: </li></ul><ul><li>Light microscopic examination usually discloses no significant abnormalities </li></ul><ul><li>The glomerular basement membranes are of unremarkable thickness and texture </li></ul><ul><li>The mesangium may be mildly expanded, but is normocellular </li></ul><ul><li>The tubulointerstitium is usually unremarkable </li></ul>
  9. 13. <ul><li>Immunofluorescence: </li></ul><ul><li>'Full house' reactivity </li></ul><ul><li>Electron microscopy: </li></ul><ul><li>Visceral epithelial cells: Unremarkable and foot processes are well preserved </li></ul><ul><li>Glomerular basement membranes: Normal appearance and texture </li></ul><ul><li>Glomerular endothelial cells: May contain tubuloreticular structures </li></ul><ul><li>Mesangium: Shows normal cell elements and an extracellular matrix with scattered fine granula electron-dense deposits </li></ul>
  10. 15. Thin Glomerular BMD <ul><li>Histopathology: </li></ul><ul><li>The capillary loops are of normal contour and may appear delicate </li></ul><ul><li>Normocellular mesangium </li></ul><ul><li>The tubules and interstitium are usually unremarkable; foamy macrophages may be seen on rare occasions in the interstitium </li></ul><ul><li>More pronounced interstitial fibrosis and tubular atrophy may be seen in elderly patients with comorbid states </li></ul>
  11. 17. <ul><li>Electron microscopy: </li></ul><ul><li>Visceral epithelial cells: </li></ul><ul><li>The visceral epithelial cells and their foot processes are well preserved. </li></ul><ul><li>Glomerular basement membranes: Morphometric measurements disclose diffuse thinning, with the mean thickness below the lower normal limit of 264 nm. Electron-dense deposits are not seen along the capillary loops </li></ul><ul><li>Glomerular endothelial cells: Unremarkable and do not contain tubuloreticular structures </li></ul><ul><li>Mesangium: Normal cell elements and an extracellular matrix without electron-dense deposits </li></ul>

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