患者女,50岁,半年前无明显诱因出现干咳、胸闷、憋气,对称,左下胸叩诊呈浊音,听诊呼吸音低。化验:WBC 6.9×109/L,ESR 30 mm/h。肝、肾功能未见异常。治疗2个月,疗效较差,行CT检查。影像学检查:胸部平片左肺中下野大片均匀致密影,上缘呈外高内低弧形影,左膈肌及肋膈角不能显示( Female, 50 years old, six months ago, no obvious incentive to appear dry cough, chest tightness, suffocation, symmetry, left lower chest percussion was voiced, auscultatory breath sounds low. Assay: WBC 6.9 × 109 / L, ESR 30 mm / h. No abnormal liver and kidney function. Treatment for 2 months, poor efficacy, line CT examination. Imaging examination: chest plain film left lung large and medium-sized uniform dense film, the upper edge was outside the arc low intracranial shadow, left diaphragm and costophrenic angle can not be displayed (