多发性肌炎是一种原因未明的、肌肉变性的结缔组织疾病。其临床表现为肌肉无力、疼痛、触痛。如合并有皮肌炎,则常伴有皮肤水肿和淡紫红色斑片,并可伴有发热等全身症状。近年来发现本病常与胃癌、乳腺癌和肺癌同时存在,因此多发性肌炎有认为可能是皮、肌对肿瘤组织的一种自体免疫反应的结果。但感染也可能是本病的一个诱发因素。鉴于本病 Polymyositis is an unexplained, muscle degenerative connective tissue disease. The clinical manifestations of muscle weakness, pain, tenderness. If combined with dermatomyositis, often accompanied by skin edema and purple patches, and may be accompanied by fever and other systemic symptoms. In recent years found that the disease often associated with gastric cancer, breast cancer and lung cancer exist, so there may be thought of polymyositis skin, muscle on the tumor tissue of an autoimmune reaction results. However, infection may also be a predisposing factor in this disease. Given this disease