minimal light microscopic changes
Post on 24-May-2015
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Minimal LM canges
• Minimal Light Microscopic Alterations– Minimal change disease– Thin glomerular basement membrane disease
(TBMD)– Lupus nephritis, class I– Immunoglobulin A (IgA) nephropathy, with no
lesion by light microscopy
Minimal Change Disease• Histopathology: • LM usually discloses no significant abnormalities• GBM- unremarkable thickness and texture• Mesangium +/- mild expansion• Podocytes +/- slightly prominent but no proliferative changes
(pseudocrescents) • Proximal tubules may contain prominent protein reabsorption
granules• The interstitium is usually delicate; foamy macrophages may be
seen on rare occasions• Acute interstitial nephritis may be seen in association with
drug-induced (particularly NSAID-induced) minimal change disease• Interstitial fibrosis and tubular atrophy may be seen in elderly
patients with comorbid states
• Immunofluorescence: • +/- fine granular reactivity for IgG within the podocyte cytoplasm (dusting). • No immune deposits present along the peripheral capillary loops or in the
mesangium
• Electron microscopy: • Visceral epithelial cells: Hallmark- diffuse effacement of visceral epithelial cell
foot processes in the absence of electron-dense deposits. • Other degenerative changes of visceral epithelial cells: microvillous degeneration,
vacuolization of the cytoplasm, increased number of lysosomes and other cytoplasmic organelles
• GBM: Usually unremarkable• Glomerular endothelial cells: Usually unremarkable and do not contain
tubuloreticular structures• Mesangium: Normal cell elements and an extracellular matrix without
electron-dense deposits
IgA
• Histopathology: • Glomeruli are normal, or they show minimal
mesangial expansion• The glomerular basement membranes are of
unremarkable thickness and texture• The mesangium may be minimally expanded, but is
normocellular• The tubulointerstitium is usually unremarkable• This form of IgA is quite common and can be
detected incidentally on renal biopsy, superimposed to any other renal disease
• Immunofluorescence: • 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
• Electron microscopy: • Visceral epithelial cells: Unremarkable, with well-preserved foot
processes• 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.
• Glomerular endothelial cells: Usually unremarkable and tubuloreticular structures are not seen.
• Mesangium: Shows normal cell elements and an extracellular matrix with scattered small fine granular electron-dense deposits
Class I lupus nephritis
• Histopathology: • Light microscopic examination usually
discloses no significant abnormalities• The glomerular basement membranes are
of unremarkable thickness and texture• The mesangium may be mildly expanded,
but is normocellular• The tubulointerstitium is usually
unremarkable
• Immunofluorescence: • 'Full house' reactivity
• Electron microscopy: • Visceral epithelial cells: Unremarkable and foot processes are
well preserved• Glomerular basement membranes: Normal appearance and
texture• Glomerular endothelial cells: May contain tubuloreticular
structures• Mesangium: Shows normal cell elements and an extracellular
matrix with scattered fine granula electron-dense deposits
Thin Glomerular BMD• Histopathology: • The capillary loops are of normal contour and
may appear delicate• Normocellular mesangium• The tubules and interstitium are usually
unremarkable; foamy macrophages may be seen on rare occasions in the interstitium
• More pronounced interstitial fibrosis and tubular atrophy may be seen in elderly patients with comorbid states
• Electron microscopy: • Visceral epithelial cells:• The visceral epithelial cells and their foot processes are well
preserved.• 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
• Glomerular endothelial cells: Unremarkable and do not contain tubuloreticular structures
• Mesangium: Normal cell elements and an extracellular matrix without electron-dense deposits
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