Crescentic glomerulonephritis seen in

RPGN presents with an acute reduction in renal function resulting in acute renal failure in a few weeks or months. It is characterized by the formation of 'crescents'(crescentic GN)outside the glomerular capillaries (extracapillary GN).' crescents' are formed from the proliferation of parietal epithelial cells lining Bowman's capsule with contribution from visceral epithelial cells and the invading mononuclear cells. The stimulus for crescent formation appears to be the presence of fibrin in the capsular space. From HARSH MOHAN 7th edition, pg no:654