PMC4678057_01
Iron deposition associated with acute tubular injury in the allograft kidney. (a) Dilated proximal tubules with focal disruption of brush border. No inflammatory infiltration is seen (hematoxylin and eosin, original magnification x400). (b) Acute tubular injury was confirmed by positive kidney injury molecule-1 staining (arrow) along the luminal surface of proximal tubules (original magnification x400). (c) Iron staining was moderately (2+) positive in the injured proximal tubules (arrow) (original magnification x400). (d) Electron photomicrograph depicting sickle shaped red blood cells (arrow) clustered in the glomerular capillary loops (original magnification x4000).
CRIT2015-528792.001.jpg
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fig1
Except for focal tubular atrophy, the majority of renal tubules were back-to-back without significant interstitial fibrosis (Figure 1(a)). An immunohistochemical stain for kidney injury molecule-1 (KIM-1) was positive along the luminal surface of some proximal tubules (Figure 1(b)), consistent with acute tubular injury. Approximately 20% of proximal tubules stained 1+ to 2+ positive for iron (Figure 1(c)), implying that the ATI was associated with iron/heme deposition from hemolyzed sickled RBCs into the renal tubules. Some irregular shaped RBCs were identified in the glomerular capillary loops, consistent with sickled RBCs (Figure 1(d)).
PMC4678057_02
Acute tubular injury caused by type 2 antibody-mediated rejection in the allograft kidney. (a) Light microscopy showed a glomerulus with lobular configuration and focal fibrin thrombi (arrow). Renal tubules are mildly dilated with mild tubulitis. Interstitial mononuclear infiltrate is also seen (hematoxylin and eosin, original magnification x100). (b) C4d diffusely positive in peritubular capillaries and glomerular capillary loops (original magnification x200). (c) Iron staining is essentially negative (original magnification x100). (d) Electron photomicrograph showed double contoured glomerular capillary loops with lucency and subendothelial deposit of fibrin (arrow), consistent with thrombotic microangiopathy (original magnification x4000).
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fig2
Sections of light microscopy revealed two biopsy cores of renal cortex containing totally ten glomeruli (Figure 2(a)). C4d staining by immunohistochemical method was strongly and diffusely positive in glomeruli and peritubular capillaries (Figure 2(b)). Iron staining was essentially negative in the renal tubules (Figure 2(c)). The glomerular basement membrane showed prominent double contour with lucent appearance and scattered foci of subendothelial fibrin deposits (Figure 2(d)).