Repeat kidney Biopsy in 19 Children with IgA Vasculitis Nephritis: A Clinicopathological Analysis

Background Immunoglobulin A vasculitis nephritis (IgAVN) is a common childhood vasculitis with heterogeneous clinical and pathological manifestations. Repeat kidney biopsy may help assess pathological evolution and guide treatment, but its role in pediatric IgAVN remains underexplored. This study aimed to evaluate the clinicopathological changes between initial and repeat biopsies and their association with treatment response and outcomes in children with IgAVN. Methods This single-center retrospective analysis included 19 pediatric IgAVN patients who underwent two kidney biopsies. Clinical, laboratory, and pathological data were compared between biopsies. Pathological evaluation used ISKDC, semiquantitative classification (SQC), and Oxford Classification (MEST-C) systems. Correlations between changes in proteinuria (Δ24hUP), eGFR slope, and pathological scores (ΔSQC, ΔActivity Index, ΔChronicity Index) were analyzed. Outcomes were classified as good (A/B) or poor (C/D) based on modified Counahan criteria. Results A total of 19 pediatric patients with IgAVN were included in this study. The cohort consisted of 12 males (63.2%) and 7 females (36.8%), with a mean age at disease onset of 10.6 ± 3.6 years. The median time from symptom onset to initial kidney biopsy was 155 days (IQR: 36, 364). A repeat kidney biopsy was performed at a median interval of 38 months (IQR: 18, 51) after the first biopsy, with the primary indications being disease recurrence (52.6%) and suboptimal treatment response (47.4%). Recurrent palpable purpura was observed in 31.6% of the patients at the time of repeat biopsy. Prior to the initial biopsy, 47.4% of the patients had received glucocorticoid therapy. The median follow-up duration for the entire cohort was 57 months (IQR: 38, 81). Microscopic hematuria improved significantly at the second biopsy ( p  = 0.012), while 24-hour proteinuria did not change significantly. Pathological scores (SQC, MEST-C) also showed no significant change. A strong positive correlation was found between Δ24hUP and ΔActivity Index (r = 0.718, p  < 0.001). 10 patients had good outcomes and 9 had poor outcomes, but no baseline or evolution parameters significantly predicted outcome. Treatment intensity increased after repeat biopsy, with more patients receiving pulse steroids and immunosuppressants. Conclusions Repeat kidney biopsy in pediatric IgAVN reveals discordance between clinical and pathological changes and supports its utility in guiding therapy adjustments. Proteinuria change strongly correlates with active pathological lesions, reinforcing its role in monitoring disease activity.