PMC10331335_01
Light and immunofluorescence microscopy. (A and B) Glomeruli show diffuse and focal nodular expansion by matrix material (circle), with superimposed mesangiolysis (asterisk) and focally prominent microaneurysm formation (arrowhead) (Jones methenamine silver and trichrome stains, 400x magnification). (C) Immunofluorescence reveals strong linear staining of basement membranes (arrows), the intensity of which is considerably greater than staining of tubular basement membranes or Bowman's capsule (200x magnification).
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The biopsy specimen for conventional light microscopy, studied with hematoxylin and eosin, periodic acid-Schiff, periodic acid-methenamine silver, and Masson trichrome stained sections, revealed glomeruli with normal size and cellularity and mesangial expansion by matrix material, consistent with diffuse and mild nodular diabetic glomerulosclerosis (Figure 1). Immunofluorescence microscopy (Figure 1) revealed strong linear staining of GBMs by IgG (3 to 4+), kappa (trace) light chain, and lambda light chain (2+).
Electron microscopy and ultrastructural evaluation. (A and B) There is electron-lucent subendothelial widening with accumulation of flocculent debris (arrow) and segmental basement membrane duplication with mesangial cell interposition (arrowhead). (C) Mesangial areas show dissolution of matrix material (asterisk) with micro-aneurysmal dilation of glomerular capillary basement membranes.
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Electron microscopy revealed GBMs with segmental subendothelial electron-lucent widening and basement membrane duplication with mesangial cell interposition and interposed trapping of electron-lucent flocculent material and occasional leukocytes (Figure 2).