儿童期发病的抗中性粒细胞胞浆抗体（ANCA）相关性血管炎（AAVs）是一组以产生ANCA为特征的全身性小血管炎。儿童原发性 AAVs 比较罕见。一般认为，AAVs的发生与免疫失调、环境及感染等因素相关，其很少在家族中聚集发生。本文报道了一对共患AAVs的双胞胎姐妹。姐姐于9岁时因“贫血20余天，尿检异常3天”就诊后，确诊为ANCA相关血管炎、ANCA相关性肾炎。妹妹在姐姐诊断后进行了尿常规筛查，发现也存在血尿和蛋白尿，并进一步确诊。2例患儿的疾病分型和分级均有所不同，临床表现和经治后的疾病转归也有很大差异。其中，姐姐肾脏病理表现为ANCA相关性肾损害合并免疫复合物沉积，表现为较差的肾脏结局；而妹妹经治疗后肾功能已恢复。后续外显子测序未发现与疾病相关变异。

Pediatric-onset anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of systemic small-vessel vasculitides characterized by ANCA production. Primary AAV in children is rare and is generally considered to arise from immune dysregulation, environmental factors, and infections, with no strong evidence of familial clustering. This report describes a pair of monozygotic twin sisters who developed AAV concurrently. The elder sister, aged 9 years, presented with "anemia for over 20 days and abnormal urinalysis findings for 3 days" and was diagnosed with ANCA-associated vasculitis and ANCA-associated nephritis. The younger sister, screened via urinalysis following her sister's diagnosis, was found to have hematuria and proteinuria, leading to a confirmatory diagnosis. Notably, the sisters exhibited distinct disease subtypes, severity grades, clinical manifestations, and treatment outcomes. The elder sister's renal pathology revealed ANCA-associated renal injury with concurrent immune complex deposits, correlating with poorer renal outcomes. In contrast, the younger sister achieved complete renal recovery after treatment. Extensive exome sequencing failed to identify pathogenic variants in either case.