Wang Yikang, Yang Mengting, Zhao Yawen, Zheng Yiming, Hao Hongjun, Gao Feng, Xiong Hui, Zhang Wei, Wang Zhaoxia, Yuan Yun
Department of Neurology, Peking University First Hospital, Beijing, China.
Beijing Key Laboratory of Neurovascular Disease Discovery, Beijing, China.
Pediatr Neurol. 2025 Jun;167:33-41. doi: 10.1016/j.pediatrneurol.2025.03.002. Epub 2025 Mar 14.
Immune-mediated necrotizing myopathy (IMNM) is a type of idiopathic inflammatory myopathies (IIMs), and the data concerning the phenotypes of pediatric IMNM are very limited. The present study aimed to elucidate the characteristics of pediatric IMNM.
We examined 116 pediatric patients with IIMs through a muscle biopsy-oriented registration study. Anti-signal recognition particle (anti-SRP) and anti-3-hydroxy-3-methylglutaryl-CoA reductase (anti-HMGCR) antibodies were detected via an immunoblot assay. A retrospective clinical, imaging, and myopathological analysis of 55 pediatric patients with IMNM was conducted.
The cohort included 38 girls and 17 boys with a median age of 7 years. Acute/subacute onset occurred in 40.0% and chronic onset in 60.0% of the patients. Proximal and neck weakness were common symptoms. The frequencies of anti-HMGCR, anti-SRP, and seronegative myopathies were 61.8%, 20.0%, and 18.2%, respectively. Chronic onset was more common in anti-HMGCR myopathy than in anti-SRP myopathy (P = 0.003). Thigh magnetic resonance imaging revealed generalized muscle edema, and the severity of fatty infiltration correlated with disease duration. Necrotizing myopathy was most common among patients with seronegative IMNM, followed by patients with anti-HMGCR and anti-SRP myopathies. Dystrophic pathology was most common among patients with anti-SRP myopathy, followed by patients with anti-HMGCR myopathy and seronegative IMNM. After steroids combined with multiple immunosuppressant therapies, 18 of 39 (46.2%) patients achieved complete or partial remission. The percent of complete remission was significantly lower in patients with anti-HMGCR myopathy compared with those with seronegative or anti-HMGCR myopathies (P = 0.030).
IMNM is common in Chinese pediatric patients with IIMs. Most patients have anti-HMGCR antibodies, are more commonly female, have chronic onset and proximal weakness, lack other organ manifestations, have disease course-related muscle fatty infiltration, and have a poor response to immunosuppression.
免疫介导性坏死性肌病（IMNM）是特发性炎性肌病（IIM）的一种类型，关于儿童IMNM表型的数据非常有限。本研究旨在阐明儿童IMNM的特征。
我们通过一项以肌肉活检为导向的登记研究，对116例儿童IIM患者进行了检查。通过免疫印迹法检测抗信号识别颗粒（抗SRP）和抗3-羟基-3-甲基戊二酰辅酶A还原酶（抗HMGCR）抗体。对55例儿童IMNM患者进行了回顾性临床、影像学和肌病理分析。
该队列包括38名女孩和17名男孩，中位年龄为7岁。40.0%的患者为急性/亚急性起病，60.0%的患者为慢性起病。近端和颈部无力是常见症状。抗HMGCR、抗SRP和血清阴性肌病的发生率分别为61.8%、20.0%和18.2%。抗HMGCR肌病的慢性起病比抗SRP肌病更常见（P = 0.003）。大腿磁共振成像显示广泛性肌肉水肿，脂肪浸润的严重程度与病程相关。坏死性肌病在血清阴性IMNM患者中最常见，其次是抗HMGCR和抗SRP肌病患者。营养不良性病理改变在抗SRP肌病患者中最常见，其次是抗HMGCR肌病和血清阴性IMNM患者。在使用类固醇联合多种免疫抑制剂治疗后，39例患者中有18例（46.2%）实现了完全或部分缓解。与血清阴性或抗SRP肌病患者相比，抗HMGCR肌病患者的完全缓解率显著较低（P = 0.030）。
IMNM在中国儿童IIM患者中很常见。大多数患者有抗HMGCR抗体，女性更为常见，起病慢性，有近端无力，无其他器官表现，有与病程相关的肌肉脂肪浸润，对免疫抑制反应较差。
