The Presence of Renal IgG Deposits in Necrotizing Crescentic Glomerulonephritis Associated with ANCA Is Not Related to Worse Renal Clinical Outcomes

Classical pauci-immune necrotizing crescentic glomerulonephritis (CGN) associated with antineutrophil cytoplasmic autoantibodies (ANCA) is characterized by the absence of renal immunoglobulin (Ig) deposits. However, IgG deposits can sometimes be present. We wanted to assess whether necrotizing CGN with IgG deposits is associated with a more severe presentation and outcome than necrotizing CGN without IgG deposits. Methods: Between November 2008 and August 2013, we retrospectively identified 158 patients from four centers who had necrotizing CGN due to primary ANCA-associated systemic vasculitis. Glomerular IgG deposits were found in 18 (11%) patients (group 1). For each patient in group 1, we selected 2 patients with classical pauci-immune necrotizing CGN with the nearest date of diagnosis in the same center (group 2, n = 36). We assessed clinical, biological, and pathological characteristics in both groups. Results: Baseline characteristics were similar in both groups, and most patients had ANCA-associated vasculitis with antibodies to myeloperoxidase (74%). Deposits displayed moderate to strong staining in 9 patients. As compared with group 2, group 1 exhibited a higher frequency of interstitial fibrosis/tubular atrophy lesions ( p = 0.024) and lower frequency of acute tubular necrosis ( p = 0.046). Nevertheless, after a mean follow-up of 30 and 26 months for group 1 and group 2, respectively, IgG deposits did not affect the renal prognosis or probability of relapse. Finally, the groups did not differ in renal or patient survival. Conclusions: IgG deposits, detected in 11% of patients with ANCA-associated necrotizing CGN, did not affect renal or patient outcomes.