Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest views were obtained with patient in upright position . There is status post sternotomy related to preceding thymectomy . Heart size is mildly enlarged , possibly related to postoperative pericardial changes . Pulmonary vasculature is not congested and there are no signs of new acute pulmonary infiltrates . The lateral pleural sinus remains free , where as the left - sided basal pleural densities have regressed . The posterior pleural sinuses remain free bilaterally . On the left base , the pleural densities have regressed . Improving aeration of the left lower lobe is noted . A loculated pulmonary thickening remains laterally and extends into a remaining thickening of the major fissure . No new pulmonary abnormalities are seen and no pneumothorax can be identified on either right or left apical area .
    OUTPUT:
    
Improvement of postoperative pleural changes in comparison with the next preceding chest examination of ___ . No new abnormalities .