Anti-neutrophil cytoplasmic antibody seropositivity in young adults aged up to 35 years: kidney histopathological findings and patient outcomes

OBJECTIVE: To investigate the clinical features, pathological renal findings, and outcomes in young adults with anti-neutrophil cytoplasmic antibody (ANCA) seropositivity. METHODS: Adults aged ≤35 years, with ANCA seropositivity, who underwent renal biopsy and received treatment comprising a combination of corticosteroids and cyclophosphamide between January 2004 and May 2018, were retrospectively enrolled. RESULTS: Thirteen patients with ANCA seropositivity were included, all of whom presented with kidney disease at diagnosis: 10 (76.9%) with ANCA-associated pauci-immune glomerulonephritis, one with ANCA-associated crescentic glomerulonephritis with immune complex deposition, one with immunoglobulin A nephropathy, and one with membranous nephropathy. The median serum creatinine level was 183.2 μmol/l (range, 55.0–1024.0 μmol/l). Respiratory symptoms (9/13 [69.2%]) and nonspecific gastrointestinal symptoms (5/13 [38.5%]) were the most common extrarenal manifestations. Remission was achieved in 10 (91%) of 11 ANCA-associated nephritis cases, and median interval from diagnosis to relapse was 30 months (range, 9–63 months). Cumulative relapse-free survival rates at 1 and 5 years were 100% and 88.9%, respectively. Overall, 1-year and 5-year renal survival rates were 80.8% and 58.9%, respectively. CONCLUSION: Renal histopathology varied in young adults with ANCA seropositivity. Although relapse rates in this young adult population were generally low, long-term renal survival rates remain unsatisfactory.