Division of Paediatric Neurology, Department of Paediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Division of Paediatric Neurology, Department of Paediatrics, King Chulalongkorn Memorial Hospital/The Thai Red Cross Society, Bangkok, Thailand.
Pediatr Rheumatol Online J. 2022 Jun 7;20(1):40. doi: 10.1186/s12969-022-00699-2.
Immune-mediated necrotizing myopathy (IMNM) is a subgroup of idiopathic inflammatory myopathies manifesting with progressive weakness, elevated serum creatine kinase (CK) levels, and necrotizing myopathic features on muscle biopsy. There is a paucity of data on the clinical presentation of IMNM in children. We report a paediatric patient who developed anti-3-hydroxy-3-methylglutaryl-CoA reductase (anti-HMGCR)-positive necrotizing myopathy after recent dengue infection.
A previously healthy 9-year-old boy presented with acute proximal muscle weakness after recovery from dengue infection. Five days after the fever subsided, he could not stand from a squatting position. He denied having skin rash, arthritis, or other systemic features. He had marked elevation of CK level of 30,833 mg/dL and was put on steroid therapy. The patient initially responded to oral prednisolone, however the weakness persisted and muscle enzymes increased as steroids were decreased. He was then referred to our hospital for further assessment. Subsequent investigation revealed anti-HMGCR positivity along with specific histopathological findings consistent with IMNM. The patient was treated with six cycles of intravenous immunoglobulin (IVIG) monthly, then followed by a gradual taper of prednisolone and oral methotrexate weekly with complete recovery in motor power.
Our report presents a child with clinical manifestations of IMNM which can be categorized as acute onset of muscle weakness following dengue infection. Two key points supporting a diagnosis in this case are clinical response after immunosuppressive therapy and absence of rashes found in juvenile dermatomyositis.
免疫介导的坏死性肌病（IMNM）是特发性炎性肌病的一个亚组，表现为进行性无力、血清肌酸激酶（CK）水平升高以及肌肉活检的坏死性肌病特征。儿童中 IMNM 的临床表现数据很少。我们报告了一例最近感染登革热后发生抗 3-羟基-3-甲基戊二酰辅酶 A 还原酶（抗 HMGCR）阳性坏死性肌病的儿科患者。
一名 9 岁的既往健康男孩在登革热感染康复后出现急性近端肌无力。发热消退后 5 天，他无法从蹲姿站立。他否认有皮疹、关节炎或其他全身症状。他的 CK 水平显著升高，达 30833mg/dL，并接受了类固醇治疗。患者最初对口服泼尼松龙有反应，但随着类固醇的减少，肌无力持续存在，肌肉酶增加。随后他被转至我们医院进一步评估。随后的检查显示抗 HMGCR 阳性，同时存在符合 IMNM 的特定组织病理学发现。患者接受了 6 个周期的每月静脉注射免疫球蛋白（IVIG）治疗，然后逐渐减少泼尼松龙和每周口服甲氨蝶呤，运动功能完全恢复。
我们的报告介绍了一例具有 IMNM 临床表现的儿童，其可归类为登革热感染后急性发作的肌无力。支持该病例诊断的两个关键点是免疫抑制治疗后的临床反应和未发现幼年皮肌炎中的皮疹。
