A new diagnostic criterion for myositis based on clinical and pathological findings

本项目旨在根据临床和病理结果提出新的肌炎诊断标准。首先，我们分析了连续126例PM/DM患者的肌肉活检中肌炎的诊断、临床和病理结果的频率。我们发现MHC-I抗原在非坏死纤维上异常表达的免疫组织化学结果是常见的，即使是稀疏的炎症细胞，也是检测炎症变化的良好标记。我们还发现，CD8阳性淋巴细胞侵入非坏死纤维（多肌炎特异性）的发生率约为5%，筋膜周围萎缩和补体复合物沉积在肌内膜毛细血管上的发生率分别为13%和23%。超微结构观察显示内皮细胞的管网状分布和肌内膜毛细血管的破坏是诊断皮肌炎的另一个很好的标志。临床与病理因素的多因素分析未发现临床与病理结果的相关性。根据以上结果，我们提出了一种基于皮肤变化和肌肉活检免疫组织化学和超微结构病理结果的新的诊断标准。通过分析187例PM/DM患者的临床表现，评价新标准的有效性。其中PM 10例（6%），dm 94例（50%），未分型肌炎62例（33%），可能肌炎21例。发现PM与DM的临床表现有较大差异，仅DM组有恶性肿瘤、胶原蛋白病变或肺纤维化。69例PM/DM患者血清细胞因子谱（GM-CSF、IFN-γ、IL-1b、2、4、5、6、8、10、TNF-a）也显示PM组与DM组之间的差异。研究结果支持了新标准的有效性。

This project aimed to propose new diagnostic criteria for myositis based on clinical and pathological findings. Firstly we analyzed the frequency of diagnostic clinical and pathological findings for myositis in biopsied muscles from 126 consecutive cases with PM/DM. We found that the immunohistochemical findings of aberrant expression of MHC-I antigen on non-necrotic fibers are frequent and are good marker for detecting inflammatory changes even with sparse inflammatory cells. We also found that the findings of the invasion of CD8 positive lymphocytes into non-necrotic fibers, which findings are specific for polymyositis are about 5%, and the frequency of the findings of perifascicular atrophy and the deposition of complement complexes on endomysial capillaries are 13% and 23% respectively. Ultrastrucural observation showed that the findings of tuburoreticular profiles in endothelial cells and destruction of endomysial capillaries are other good markers for diagnosis of dermatomyositis. The multifactor analysis between clinical and pathological factors did not show correlation between clinical and pathological findings. Following above results, we proposed a new diagnostic criterion based on skin changes and immunohistochemical and ultrastructural pathological findings in biopsied muscle. The validity of the new criteria was assessed through analyzing clinical pictures of consecutive 187 cases with PM/DM. The 187 cases were classified into 10 PM cases (6%), 94DM cases (50%), 62 unclassified myositis cases (33%) and 21 probable myositis cases. It was revealed that the clinical pictures between PM and DM are quite different and the cases with malignancy, collagen disease or pulmonary fibrosis were found only in DM group. The serum cytokine profiles (GM-CSF、 IFN-γ、IL-1b,2,4,5,6,8,10,TNF-a) assessed in 69 PM/DM cases also showed the difference between PM and DM groups. The results supported the validity of the proposed new criteria.