Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette is normal in size . The mediastinal and hilar contours are normal . There is an ill - defined opacity occupying the left upper lobe and mid left lung , which is concerning for an acute infectious process . This area likely corresponds to incompletely imaged tree - in - ___ opacities seen on prior dedicated neck CT . The right hemi thorax is clear . There is no pleural effusion . There is no pneumothorax . Subcutaneous emphysema is present the right neck , better assessed on prior neck CT examination .
    OUTPUT:
    
1 . Ill - defined focal opacity in the left upper lobe and left mid lung field , concerning for an acute infectious process , likely corresponding to incompletely imaged tree - in - ___ opacities on prior dedicated neck CT . 2 . Redemonstration of subcutaneous emphysema in the right neck , better assessed on prior neck CT .