Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A new area of consolidation has rapidly developed within the left lower lobe , predominantly in the retrocardiac region . Considering clinical history of cough , leukocytosis and fever , this is concerning for an evolving pneumonia in this region . Post - treatment changes in the right hemithorax appear similar to the prior study , and cardiac silhouette enlargement appears unchanged , corresponding to pericardial effusion on prior CT .
    OUTPUT:
    
1 . New left lower lobe airspace consolidation concerning for developing pneumonia or acute aspiration event . 2 . Stable post - treatment changes in right hemithorax .