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126例PM/DM患者的肌肉活检中肌炎的诊断、临床和病理发现的频率。我们发现，非坏死纤维上MHC-I抗原异常表达的免疫组化结果是常见的，并且即使是稀疏的炎性细胞也是检测炎性变化的良好标记物。我们还发现，CD 8阳性淋巴细胞侵入非坏死纤维的发现，这一发现是特异性的多发性肌炎约为5%，和束周萎缩和补体复合物沉积的发现的频率分别为13%和23%。超微结构观察显示，内皮细胞的管状网状轮廓和肌内膜毛细血管的破坏也是诊断皮肌炎的良好标志。临床与病理因素的多因素分析未显示临床与病理的相关性。根据上述结果，我们提出了一个新的诊断标准，根据皮肤的变化和免疫组化和超微病理学检查肌肉活检的结果。通过对187例PM/DM患者的临床资料分析，评价新标准的有效性。其中PM 10例（6%），DM 94例（50%），未分类肌炎62例（33%），疑似肌炎21例。结果表明，PM与DM的临床表现有很大不同，仅DM组有恶性肿瘤、胶原病和肺纤维化。69例PM/DM患者的血清细胞因子（GM-CSF、IFN-γ、IL-1b、2、4、5、6、8、10、TNF-α）水平在PM组和DM组之间也有差异。研究结果支持了所提出的新标准的有效性。

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.