Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable upright view of the chest . In this patient with known left lower lobe mass , a fiducial marker projects over the cardiac silhouette . There is interval improvement in overall aeration in the left upper lobe . Mild persistent perihilar opacity persists which may represent residual atelectasis or may be related to known hilar mass . There is stable blunting of the right CP angle which may represent pleural thickening or tiny effusion . The cardiomediastinal silhouette appears grossly unchanged . The imaged osseous structures appear intact .
    OUTPUT:
    
Improved aeration in the left upper lobe . Persistent perihilar opacity and left lower lobe mass as seen on prior PET - CT .