Necrotizing medullary lesions in patients with ANCA associated renal disease

One hundred and five renal specimens from patients with antineutrophil cytoplasmic antibody and antiglomerular basement membrane antibody-associated diseases were reviewed for necrotizing lesions involving the renal medulla. Necrotizing medullary lesions were identified in eight of 56 cases in which medullary tissue was present. All eight were in patients with antineutrophil cytoplasmic antibody (ANCA) associated disease (seven, C-ANCA; one P-ANCA). Four types of medullary lesions were identified; necrotizing capillaritis (seven cases), necrotizing arteriolitis (two cases), pathergic granulomas (three cases) and papillary tip necrosis (one case). Both medullary arteriolitis and medullary peritubular capillaritis developed without corresponding cortical arteriolitis or cortical peritubular capillaritis. Although necrotizing glomerulonephritis was present in seven of eight patients, its activity did not parallel the severity of the medullary lesions. We conclude that several forms of necrotizing medullary vascular lesions may develop in ANCA-associated disease and that there is discordance between state of activity and types of vessel affected between cortical and medullary vascular compartments.