肢带型肌营养不良2B型与多发性肌炎的临床及病理鉴别诊断

目的 分析肢带型肌营养不良2B型(LGMD2B)与多发性肌炎(PM)的临床、病理诊断与鉴别诊断要点.方法 对8例首诊为PM,再诊时高度怀疑LGMD2B的患者做开放式骨骼肌活体组织检查,行组织化学及抗dysferlin、dystrophins、sarcoglycans、MHC-Ⅰ、CD8单克隆抗体免疫组织化学染色,与4例PM进行临床、病理对比分析.结果 (1)组织化学染色2组患者均呈不同程度的肌纤维变性、坏死,炎细胞浸润;临床可疑LGMD2B患者dystrophins、sarcoglycans蛋白表达正常,dysferlin蛋白表达缺失,MHC-Ⅰ弱或阴性表达,少数炎细胞CD8阳性表达,因此确诊为LGMD2B;4例PM患者肌纤维膜上dysferlin蛋白表达正常,MHC-Ⅰ在肌纤维膜及炎细胞浸润区呈强阳性表达,部分炎细胞CD8阳性表达.(2)LGMD2B与PM临床均表现为近端肌无力,血肌酸激酶显著增高,肌电图呈肌源性异常.LGMD2B肌痛不明显,红细胞沉降率、C反应蛋白正常,有别于PM.结论 LGMD2B与PM在临床、骨骼肌组织化学染色病理上相似,易误诊;LGMD2B患者dysferlin蛋白表达缺失及PM患者的MHC-Ⅰ、CD8强阳性表达可作为两者诊断与鉴别诊断的重要方法.

Clinical and pathological analysis of limb-girdle muscular dystrophy type 2B misdiagnosed as polymyositis

Objective To diagnose and differentially diagnose limb-girdle muscular dystrophy type 2B(LGMD2B)and polymyositis (PM) based on clinical and pathological characteristics. Methods Muscle biopsics were obtained from 8 patients suspected with LGMD2B who were initially diagnosed with PM.The clinical and pathological data from 8 cases of LGMD2B and 4 cases of PM by using histo-and immunohistochemistry with anti-dysferlin,dystrophins,sarcoglycans,MHC-Ⅰ,CD8 monoclonal antibodies were compared.Results (1) LGMD2B and PM shared similar pathological presentations including muscle fibet degeneration and necrosis in various degree,proliferation of connective tissue,and inflammatory cell infiltration.Normal stains of dystrophins and sarcoglycans were observed.whereas absent or very faint staining of dysfedin observed in muscle biopsies of 8 patients confirmed the diagnosis of LGMD2B.while normal stains of dysferlin on sarcolemma were observed in the 4 cases of PM.MHC-Ⅰ was weakly expressed or absent in LGMD2B.while strongly expressed on sarcolemma in PM and the infiltration area of inflammation cells.The expression of CD8 on a few inflammatory cells were positive in LGMD2B.while some inflammatory cells were positive in PM.(2)Both LGMD2B and PM shared similar presentation,including proximal muscle weakness,remarkable elevation of CK,myopathic changes in electromyography.Patients with LGMD2B did not complain of apparent muscle pain.and their erythrocyte sedimentation rate and Creactive protein were in normal range.which could be used as marker to differentiate from patients with PM.Conclusions Clinically and pathologically LGMD2B and PM are presented similarly and likely to be misdiagnosed.The absence of dysferlin in LGMD2B and high expression of MHC-Ⅰ and CD8 in PM are the key index of the diagnosis and differential diagnosis between LGMD2B and PM.