Fig. 1

Renal Biopsy Findings: a-c: Biopsy #1. a: A circumferential cellular crescent is seen (PAS, × 400) b: There is prominent tubular atrophy and interstitial fibrosis along with interstitial foam cells (arrowheads) (H&E, × 300). Most arterioles are mildly thickened, but an arteriole shows intraluminal fibrin with karyorrhectic debris (inset, JMS) c: Lamina densa lamellation (arrows) is seen along the glomerular basement membrane on electron microscopy (× 8000). d-i: Biopsy #2. d: Glomerulus with fibrin thrombus and fibrinoid necrosis near the vascular pole (JMS × 400) e: Arteriole with fibrin thrombus, karyorrhectic debris and extravasated red blood cells. No vasculitis is seen (trichrome × 400). f: Ischemic retraction and thickening of the glomerular basement membranes on electron microscopy. Mesangiolysis and expansion of the subendothelial space is seen (arrow) (× 3000). g: Tissue antigen preservation documented with type IV collagen α2 staining h: Complete absence of α3 staining in the glomerular and tubular basement membranes i: Absent glomerular basement membrane staining with type IV collagen α5. But linear staining along the Bowman’s capsule and distal tubular basement membranes is preserved