目的 总结抗黑色素瘤分化相关基因5抗体（MDA5）相关幼年型皮肌炎（JDM）的临床特征，研究其治疗及评估。方法 回顾性分析2019年1月至2022年5月住院的5例抗MDA5相关JDM患儿的基本信息、临床表现、实验室及影像学检查、治疗及预后等临床资料。结果 5例患儿中男3例、女2例，5例均有典型的高春疹/征，3例有皮肤溃疡表现，2例出现皮肤钙化，1例有指端坏死。5例患儿肌力均正常，但肌肉核磁共振均异常。肌炎特异性抗体均为抗MDA5抗体阳性，3例合并抗Ro-52阳性。5例高分辨CT均示间质性肺病，只有1例出现气促，2例涎液化糖链抗原（KL-6）升高；2例有消化道受累。5例均使用激素，4例使用环磷酰胺作为最初免疫抑制剂，2月内均可部分缓解。结论 抗MDA5相关JDM起病年龄偏小，临床表现以典型皮疹为主，肌肉受累表现不明显，以临床无肌病性皮肌炎为主，并高发间质性肺病；抗MDA5滴度、高分辨CT、KL-6检查对于诊断及疾病疗效评估尤为重要；治疗主要甲基泼尼松龙联合免疫抑制剂，联合托法替布者治疗效果良好。

Objective To summarize the clinical features of anti-melanoma differentiation-associated gene 5 antibody (MDA5)-positive juvenile dermatomyositis (JDM), and to study its treatment and evaluation. Methods The basic information, clinical manifestations, laboratory and imaging examinations, treatment and prognosis of 5 children with anti-MDA5-positive JDM who were hospitalized from January 2019 to May 2022 were retrospectively analyzed. Results All 5 patients (3 boys and 2 girls) had typical Gottron rash/sign, 3 had skin ulcer, 2 had skin calcification, and 1 had digital necrosis. All the 5 patients had normal muscle strength, but abnormal muscle MRI. Myositis specific antibodies were positive for anti-MDA5 antibodies in all children, and 3 patients were positive for anti-Ro-52. All 5 patients showed interstitial lung disease on high-resolution CT. Only 1 patient had shortness of breath, 2 had elevated KL-6, and 2 had digestive tract involvement. All 5 patients were treated with corticosteroids, and 4 were treated with cyclophosphamide as the initial immunosuppressant, and all of them were partially relieved within 2 months. Conclusions The onset age of anti-MDA5-related JDM is relatively low, the clinical manifestations are primarily typical rash, muscle involvement is not evident, primarily clinically amyopathic dermatomyositis, and the incidence of interstitial lung disease is high. Anti-MDA5 antibody titer, high-resolution CT, KL-6 examination is particularly important for diagnosis and evaluation of disease efficacy. The main treatment is methylprednisolone combined with immunosuppressive agents. The combined treatment with tofaciib is effective.