Histopathological atlas of renal diseases: ANCA-associated vasculitis (Second part).

In the first part of Histopathological Atlas of Renal Diseases we described the typical morphological features of Anca-associated vasculitis. The histological features in Wegener's granulomatosis, Micropolyarteritis and its renal-limited variant, are characterized by "pauci immune" necrotizing extracapillary glomerulonephritis. The cellular composition of glomerular crescent and the mechanisms underlying crescent formation are still incompletely understood. The recent availability of monoclonal antibodies directed against epithelial cells and leucocytes allowed a more precise identification of the crescent cells. In this chapter we will describe the prevalent presence of monocytes in the crescents, the possible mechanisms of recruitment of these cells and the morphological consequences of this glomerular infiltration for the chronic progression of lesions.