Pauci-immune necrotizing lupus nephritis: report of two cases.

Two cases of pauci-immune necrotizing glomerulonephritis are presented. The glomerular lesions featured proliferative and necrotizing changes morphologically compatible with World Health Organization class III and IV lupus nephritis. However, immunofluorescent microscopy and electron microscopy failed to reveal any significant deposits of immune complexes. These findings appear to indicate that the glomerulopathy in this rare form of lupus nephritis is unrelated to the usual pathogenetic mechanism, namely, deposition of circulating or locally formed immune complexes. It is suggested that the pathogenesis of pauci-immune necrotizing lupus nephritis may involve an alternate mechanism of glomerular injury that is independent of antigen and antibody reactions and primarily involves neutrophils, lymphocytes, and monocytes.