患者　男 ,4 7岁。无明显诱因出现阵发性胸痛不适 2天 ,不伴胸闷、憋气及咳嗽等。查体 :一般情况好 ,未见明确阳性体征。实验室检查无特殊。胸部平片 :右上纵隔略增宽 ,出现内外 2条光滑连续的轮廓线 ,靠外的轮廓线密度稍淡 ,走行似右头臂血管影 (图 1) ,心、肺、膈等未见异常 Patient male, 47 years old. No obvious incentive to paroxysmal chest pain discomfort for 2 days, without chest tightness, suffocation and coughing. Physical examination: the general situation is good, no clear positive signs. No special laboratory test. Chest plain film: the upper right mediastinum slightly wider, there are two smooth inside and outside the outline of contour line outside the slightly lighter density, walking like right arm vascular shadow (Figure 1), heart, lung, diaphragm and so on were normal