Unusual Biopsy Findings in a Hepatitis C–Infected White Man With Cryoglobulinemia, Purpuric Rash, and Renal Failure  Sumit Mohan, MBBS, MPH, Manasvi Jaitly, MBBS, MS, Jen-Tse Cheng, MD, Vivette D. D’Agati, MD, Velvie A. Pogue, MD  American Journal of Kidney Diseases  Volume 48, Issue 3, Pages 513-517 (September 2006) DOI: 10.1053/j.ajkd.2006.03.088 Copyright © 2006 National Kidney Foundation, Inc. Terms and Conditions

Fig 1 A glomerulus is infiltrated by eosinophilic amorphous material that expands the mesangium. The interstitium is diffusely expanded by moderate edema and fibrosis accompanied by a moderate interstitial inflammatory infiltrate of mononuclear leukocytes. Proximal tubules show widespread degenerative and regenerative changes (hematoxylin and eosin; original magnification ×100). American Journal of Kidney Diseases 2006 48, 513-517DOI: (10.1053/j.ajkd.2006.03.088) Copyright © 2006 National Kidney Foundation, Inc. Terms and Conditions

Fig 2 Mesangial material is weakly periodic acid–Schiff positive and paler than the matrix of the glomerular basement membrane (periodic acid–Schiff; original magnification ×250). American Journal of Kidney Diseases 2006 48, 513-517DOI: (10.1053/j.ajkd.2006.03.088) Copyright © 2006 National Kidney Foundation, Inc. Terms and Conditions

Fig 3 Congo red stain for amyloid viewed under polarized light showed apple green birefringence in the distribution of the glomerular mesangium and afferent arteriole (Congo red stain; original magnification ×100). American Journal of Kidney Diseases 2006 48, 513-517DOI: (10.1053/j.ajkd.2006.03.088) Copyright © 2006 National Kidney Foundation, Inc. Terms and Conditions

Fig 4 By electron microscopy, the glomerular basement membrane is infiltrated by randomly oriented nonbranching fibrils of 8 to 10 nm in diameter that extend from the subendothelial to the subepithelial aspect, forming spicular projections toward the urinary space. There is overlying effacement of foot processes (electron micrograph; original magnification ×6,000). American Journal of Kidney Diseases 2006 48, 513-517DOI: (10.1053/j.ajkd.2006.03.088) Copyright © 2006 National Kidney Foundation, Inc. Terms and Conditions

Fig 5 Immunoperoxidase stain for SAA protein shows positivity in the distribution of the glomerulus and small arteries, consistent with AA amyloidosis (immunoperoxidase; original magnification ×100). American Journal of Kidney Diseases 2006 48, 513-517DOI: (10.1053/j.ajkd.2006.03.088) Copyright © 2006 National Kidney Foundation, Inc. Terms and Conditions