Carroll Matthew B, Newkirk Michelle R, Sumner Nathan S
From the *Keesler Medical Center, Ocean Springs, MS; and †Brooke Army Medical Center, Fort Sam Houston, TX.
J Clin Rheumatol. 2016 Oct;22(7):376-80. doi: 10.1097/RHU.0000000000000427.
Necrotizing autoimmune myopathy (NAM) is a recently recognized entity within the spectrum of idiopathic inflammatory myopathies. Diagnosis critically rests on histopathologic demonstration of macrophage predominant myocyte destruction, with few to no lymphocytes. We report our experience with identifying and treating this subset of inflammatory myositis, highlighting the importance of muscle biopsy in diagnosis, association with statin use and malignancy, and challenges of therapy.We present 3 cases that presented to 2 hospitals within our academic system in calendar year 2014 with acute/subacute onset of profound proximal muscle weakness and markedly elevated creatine kinase levels. All patients had been exposed to statins for varying periods. While each electromyogram (EMG) study showed changes with a diffuse inflammatory myopathy, it was not until muscle biopsy was performed when histopathologic features consistent with NAM solidified the diagnosis in all 3 cases. While high-dose glucocorticoids helped provide some degree of improvement in symptoms, none of our cases returned to their preillness baseline independent functioning. Additional immunosuppressive therapy was considered in each case but limited because of comorbidities.These cases demonstrate the importance of pursuing muscle biopsy in all patients with proximal muscle weakness and markedly elevated creatine kinase levels. While symptoms appear consistent with polymyositis, only through muscle biopsy can the diagnosis of NAM be made. Statins have been implicated in NAM, acting through an antibody-dependent mechanism. Combination immunosuppressive therapy has been advocated, but our patient's comorbidities precluded safe use of medications beyond glucocorticoids.
坏死性自身免疫性肌病（NAM）是特发性炎性肌病范围内最近才被认识的一种疾病。诊断关键取决于组织病理学显示巨噬细胞为主的肌细胞破坏，淋巴细胞很少或没有。我们报告了我们在识别和治疗这一炎性肌炎亚组方面的经验，强调了肌肉活检在诊断中的重要性、与他汀类药物使用和恶性肿瘤的关联以及治疗挑战。我们介绍了2014年日历年在我们学术系统内的2家医院就诊的3例患者，他们均急性/亚急性起病，表现为严重的近端肌无力和肌酸激酶水平显著升高。所有患者都曾在不同时间段使用过他汀类药物。虽然每项肌电图（EMG）检查都显示有弥漫性炎性肌病的改变，但直到进行肌肉活检时，与NAM一致的组织病理学特征才在所有3例中确诊。虽然高剂量糖皮质激素有助于症状有一定程度的改善，但我们的病例均未恢复到病前的基线独立功能状态。每例均考虑了额外的免疫抑制治疗，但由于合并症而受到限制。这些病例表明，对于所有近端肌无力和肌酸激酶水平显著升高的患者，进行肌肉活检很重要。虽然症状看似与多发性肌炎一致，但只有通过肌肉活检才能做出NAM的诊断。他汀类药物与NAM有关，通过抗体依赖机制起作用。有人主张联合免疫抑制治疗，但我们患者的合并症使除糖皮质激素外的药物无法安全使用。
