Immune-mediated necrotizing myopathy with antibodies against 3-hydroxy-3-methylglutaryl-coenzyme A reductase is a subgroup of idiopathic inflammatory myopathies mainly described in adults and requiring long term immunomodulatory therapy for remission. Pediatric patients have been reported as small series or sporadic cases. We report an eight-year-old girl with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myopathy, presenting with subacute proximal limb weakness, high creatine kinase and a muscle biopsy displaying necrotizing pattern, initially diagnosed as limb-girdle muscular dystrophy, but subsequently negative genetic testing. A noteworthy spontaneous improvement in her weakness suggested the possibility of an acquired autoimmune myopathy, confirmed by positive testing of anti-HMGCR antibodies titers. After four years of follow-up, she maintains normal strength with high levels of anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody. This patient shows that spontaneous fluctuations and spontaneous long-lasting symptomatic remission can occur in patients with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myopathy. Some patients could present a wane and wax clinical course, an important aspect when assessing response to therapy.

中文翻译：

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一例抗 3-羟基-3-甲基戊二酰辅酶 A 还原酶肌病儿科患者的自发症状改善

具有抗 3-羟基-3-甲基戊二酰辅酶 A 还原酶抗体的免疫介导的坏死性肌病是特发性炎症性肌病的一个亚组，主要见于成人，需要长期免疫调节治疗才能缓解。儿科患者已被报告为小范围病例或散发病例。我们报告了一名患有抗 3-羟基-3-甲基戊二酰辅酶 A 还原酶肌病的 8 岁女孩，表现为亚急性近端肢体无力、高肌酸激酶和肌肉活检显示坏死模式，最初诊断为肢带肌营养不良，但随后的基因检测呈阴性。她虚弱的一个值得注意的自发改善表明可能患有获得性自身免疫性肌病，这通过抗 HMGCR 抗体滴度的阳性测试得到证实。经过四年的追踪，她通过高水平的抗 3-羟基-3-甲基戊二酰辅酶 A 还原酶抗体保持正常强度。该患者表明，抗 3-羟基-3-甲基戊二酰辅酶 A 还原酶肌病患者可出现自发波动和自发性长期症状缓解。一些患者可能会出现逐渐减弱的临床病程，这是评估治疗反应时的一个重要方面。