Clinicopathological features of antineutrophil cytoplasmic antibodies associated vasculitis with glomerular IgA deposits

Objective To investigate the clinical manifestations, renal pathology and prognosis of antineutrophil cytoplasmic antibody-associated small-vessel vasculitis (AAV) accompanied with renal glomerular IgA deposition. Methods A retrospective analysis was performed at the First Affiliated Hospital of Zhejiang University College of Medicine. Patients diagnosed with AAV associated renal injury by renal biopsy from February 2004 to February 2017 were enrolled. Patients with antiglomerular basement membrane antibody-mediated nephritis, systemic lupus erythematosus nephritis, Henoch Schonlein purpura nephritis, hepatitis B virus associated nephritis and other known etiology were excluded. According to immunofluorescence examination, the patients were divided into IgA deposition group and pauci-immune complex deposition group. The differences in clinical manifestation, pathological features and prognosis were compared between groups. Results A total of 150 AAV cases were included, among which 25 cases were with IgA deposition and 125 cases with pauci-immune complex deposition. The level of serum albumin in IgA deposition group was higher than that in pauci-immune complex deposition group [(35.0±6.2) g/L vs (32.6±5.3) g/L, P=0.049], but the titer of MPO-ANCA was lower [24.8(10.4, 71.8) U/ml vs 63.0(21.9, 100.0) U/ml, P=0.044] in IgA deposition group. There was no significant difference between two groups in other laboratory indexes and renal pathological findings. The median follow-up time was 15.2 months in IgA deposition group and 8.9 months in pauci immune complex deposition group. During the follow-up there were 8 patients (32.0%) in IgA deposition group and 29 patients (23.2%) in pauci immune complex deposition group on maintaining dialysis; 2 patients (8.0%) in IgA deposition group and 7 patients (5.6%) in pauci immune complex deposition group died. There was no significant difference between two groups in patients' outcomes. Conclusions AAV patients with glomerular IgA deposition and AAV patients with typical glomerular immunoglobulin complex deposition are similar as regards clinical appearance and prognosis.