Synopsis

 early stage of pauci-immune crescentic glomerulonephritis

• segmental fibrinoid necrosis
• nuclear debris
• glomerular basement membrane disruption

 well-developed cellular crescent
 collapse of small amount of remaining glomerular tuft
 segmental fibrinoid necrosis
 extracapillary fibrin
 necrosis

Immunofluorescence

 negative

Ultrastructure

 electron dense areas
 absence of deposits along the capillary wall
 glomerular basement membrane break

• leads to exudation of plasma proteins which stimulates proliferation of parietal epithelial cells, leading to crescent formation.

Etiology

 Wegener granulomatosis
 microscopic polyangiitis