Pauci-immune Necrotizing Crescentic Glomerulonephritides: Wegener's Granulomatosis/Microscopic Polyangiitis  Agnes Fogo, MD  American Journal of Kidney Diseases  Volume 32, Issue 2, Pages E1-E2 (August 1998) DOI: 10.1053/S0272-6386(13)90007-X Copyright © 1998 National Kidney Foundation, Inc. Terms and Conditions

Fig 1 Segmental fibrinoid necrosis with nuclear debris and glomerular basement membrane disruption, typical of early stage of pauci-immune crescentic glomerulonephritis, diagnosed clinically as Wegener's granulomatosis in this case. The morphological differential includes microscopic polyangiitis and Wegener's granulomatosis, which cannot be distinguished morphologically from the kidney biopsy. Immunofluorescence studies are negative in both of these diseases, and few if any, electron dense areas are found by electron microscopy (Jones silver stain; original magnification ×400). American Journal of Kidney Diseases 1998 32, E1-E2DOI: (10.1053/S0272-6386(13)90007-X) Copyright © 1998 National Kidney Foundation, Inc. Terms and Conditions

Fig 2 Well-developed cellular crescent with collapse of small amount of remaining glomerular tuft with segmental fibrinoid necrosis and extracapillary fibrin and necrosis in pauci-immune crescentic glomerulonephritis, consistent with Wegener's granulomatosis or microscopic polyangiitis. Immunofluorescence studies were negative (Jones silver stain; original magnification ×400). American Journal of Kidney Diseases 1998 32, E1-E2DOI: (10.1053/S0272-6386(13)90007-X) Copyright © 1998 National Kidney Foundation, Inc. Terms and Conditions

Fig 3 Electron microscopy shows the absence of deposits along the capillary wall in a case of pauci-immune crescentic glomerulonephritis, consistent with Wegener's granulomatosis. The glomerular basement membrane break, which is the unit lesion leading to exudation of plasma proteins which stimulates proliferation of parietal epithelial cells, leading to crescent formation, is illustrated (transmission electron microscopy; original magnification ×8,000). American Journal of Kidney Diseases 1998 32, E1-E2DOI: (10.1053/S0272-6386(13)90007-X) Copyright © 1998 National Kidney Foundation, Inc. Terms and Conditions

Fig 4 Fig 4. Open lung biopsy illustrating necrotizing granulomatous inflammation and vasculitis, with negative cultures typical and diagnostic of Wegener's granulomatosis (hematoxylin & eosin; original magnification ×100). American Journal of Kidney Diseases 1998 32, E1-E2DOI: (10.1053/S0272-6386(13)90007-X) Copyright © 1998 National Kidney Foundation, Inc. Terms and Conditions