重症肌无力合并炎症性肌病二例报道并文献复习

Myasthenia gravis combined with inflammatory myopathy:two cases report and literature review

目的探讨重症肌无力(MG)合并炎症性肌病(IM)患者的临床表现、肌肉病理及血清免疫学特点,以提高临床医生对本病的认识。方法收集山东大学齐鲁医院于2017至2019年诊治的2例MG合并IM患者的临床资料,并结合文献进行回顾性分析。结果例1,71岁女性,因“进行性呼吸困难1个月,心肺复苏术后4 d”入院。入院前胸部CT示前纵隔占位。入院后发现四肢无力并脱机困难,查肌酸激酶1600 U/L,肌电图呈活动性肌病表现,肌炎抗体阴性,进一步行肌肉活组织检查(活检),病理符合IM表现,同时新斯的明试验、抗乙酰胆碱受体(AchR)抗体及抗横纹肌抗体(ASA)阳性,诊断为MG合并IM。例2,72岁男性,因“进行性吞咽困难并四肢无力2年余,再发四肢无力3个月”入院。2年余前首次发病1个月前行胸腺瘤切除术,当时查肌酸激酶474 U/L,肌电图呈肌源性损害,肌炎抗体阴性,肌肉活检病理符合IM表现,结合既往双侧面部及肘关节伸侧皮疹病史,诊断为皮肌炎,给予泼尼松口服后病情明显好转。3个月前再次出现四肢无力伴皮疹,复查肌酸激酶升至1167 U/L,重复神经电刺激、新斯的明试验、抗AchR抗体及ASA均为阳性,修正诊断为MG合并IM。本组2例患者均合并胸腺瘤,临床上均无波动性肌无力、眼睑下垂及复视等典型MG表现,但抗AchR抗体及ASA均阳性,且病理上虽呈现IM病理改变,但肌炎抗体均阴性,与既往文献报道一致。结论MG合并IM时临床表现常不典型,易合并胸腺瘤,其免疫病理机制不同于单纯的MG或IM。ASA是否为IM的致病性抗体尚待进一步研究。

Objective To explore the clinical,muscle pathological and immunological characteristics of myasthenia gravis(MG)combined with inflammatory myopathy(IM)in order to improve the clinician′s understanding of this disease.Methods The clinical data of two patients with MG combined with IM who admitted to Qilu Hospital,Cheeloo College of Medicine,Shandong University from 2017 to 2019 were collected and retrospectively analyzed with literature review.Results Case 1,a 71-year-old female,presented with progressive dyspnea for one month,and was rescued from cardiopulmonary resuscitation four days before.Chest CT showed mediastinum space occupying before admission.After admission,she had difficulty weaning and weakness in his four limbs,and creatine kinase(CK)increased to 1600 U/L,electromyogram indicated an active myopathy,anti-myositis antibodies were negative,but further muscle pathology was consistent with IM,and neostigmine test,anti-acetylcholine receptor(AchR)antibody and anti-striational antibody(ASA)were positive,so MG combined with IM was diagnosed.Case 2,a 72-year-old male,presented with progressive dysphagia and limbs weakness for more than two years after removal of his thymoma one month before.His CK was 474 U/L,electromyography showed myogenic change,myositis antibodies were negative,but further muscle pathology was consistent with IM,so dermatomyositis was diagnosed combined with the history of rash on his bilateral face and extensor surfaces of elbows.After oral prednisone,his condition significantly improved.However,the limb weakness and rash reappeared three months before.After reexamination,his CK was increased to 1167 U/L,and repetitive nerve stimulation,neostigmine test,anti-AchR antibody and ASA were positive.His diagnosis was revised as MG combined with IM.In this group,both of the two patients had thymoma,and there were no typical MG manifestations such as fluctuating muscle weakness,ptosis and diplopia,but anti-AchR antibody and ASA were positive.Although the muscle pathology of them was consistent with IM,myositis antibodies were negative in both of them,consistent with previous reports.Conclusions The clinical manifestations of MG combined with IM are often atypical,often associated with thymoma.The mechanism of immunopathology of MG combined with IM may be different from that of pure MG or IM.Whether ASA is pathogenic in IM remains to be further studied.