Renal amyloidosis with crescents.

An unusual case of renal amyloidosis associated with extensive crescents is reported. Light and electron microscopic examination revealed that deposits of amyloid were almost invariably involved in the locations in which proliferations of epithelial cells in the capsular spaces had merged with the glomerular tufts. Gaps or fractures of the capillary walls were present at such sites, in which amyloid fibrils were mingled with thrombic material containing fibrin. It is highly conceivable that the gaps apparently induced by amyloid deposition, with leakage of fibrin-fibrinogen into the capsular space, play a crucial role in the development of the extracapillary proliferation.