Supplementary Material for: Multi-organ Relapse Following COVID-19 in MPO-ANCA-Associated Vasculitis: A Case Report

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a complex systemic autoimmune disease characterized by small vessel vasculitis. Typically, the relapse rate is lower in patients with end-stage kidney disease (ESKD) than in those with chronic kidney disease (CKD), prior to dialysis. Here, we report a rare case of multi-organ relapse in a patient with myeloperoxidase (MPO)-AAV who underwent hemodialysis following coronavirus disease 2019 (COVID-19). A man in his 70s with type 2 diabetes and hypertension was undergoing maintenance hemodialysis for ESKD resulting from MPO-AAV glomerulonephritis. Following severe acute respiratory syndrome coronavirus 2 infection, the patient was hospitalized for persistent nausea and vomiting. No significant findings were observed, including in endoscopy. However, the patient experienced severe symptoms that hindered oral intake and was refractory to pharmacological therapy. Additionally, despite receiving antibiotics and antituberculosis treatment, the patient experienced persistent unexplained pleural effusion. Moreover, the patient’s level of consciousness rapidly deteriorated during hospitalization. Although C-reactive protein levels and MPO-ANCA titers were elevated, no evidence of infection was detected on brain imaging or cerebrospinal fluid analysis. Therefore, we diagnosed this case as a relapse of AAV and promptly administered methylprednisolone pulse therapy and rituximab. Subsequently, all aforementioned symptoms in the patient improved, and the current ANCA levels remain negative. Thus, the relapse of AAV after COVID-19 is rare; however, it can present in several ways in patients undergoing dialysis. Therefore, clinicians should closely monitor ANCA titers and subtle symptoms, even in patients with dialysis-dependent AAV.

抗中性粒细胞胞浆抗体（Anti-neutrophil cytoplasmic antibody, ANCA）相关性血管炎（ANCA-associated vasculitis, AAV）是一类以小血管炎为核心特征的复杂全身性自身免疫性疾病。通常情况下，终末期肾病（end-stage kidney disease, ESKD）患者的疾病复发率低于透析前的慢性肾病（chronic kidney disease, CKD）患者。本文报告1例罕见病例：一名70余岁男性患者，合并2型糖尿病与高血压病史，因髓过氧化物酶（myeloperoxidase, MPO）相关性ANCA血管炎（MPO-AAV）引发终末期肾病，目前接受维持性血液透析治疗。在感染严重急性呼吸综合征冠状病毒2（severe acute respiratory syndrome coronavirus 2, SARS-CoV-2）后，患者因持续性恶心呕吐入院。内镜及其他相关检查未发现显著异常，但患者出现严重症状，无法经口进食，且对药物治疗应答不佳。此外，尽管接受了抗生素与抗结核治疗，患者仍存在持续不明原因的胸腔积液。住院期间，患者意识水平快速恶化。虽C反应蛋白（C-reactive protein）水平及MPO-ANCA滴度升高，但脑部影像学与脑脊液（cerebrospinal fluid）分析未检测到感染证据。据此，临床团队诊断该病例为AAV复发，并立即给予甲泼尼龙冲击治疗（methylprednisolone pulse therapy）与利妥昔单抗（rituximab）治疗。后续患者所有前述症状均得到改善，当前ANCA水平仍维持阴性。综上，COVID-19感染后AAV复发较为罕见，但在接受透析治疗的患者中可呈现多种临床表现形式。因此，临床医师应密切监测ANCA滴度与细微临床症状，即使是依赖透析的AAV患者。