Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle patchy opacity at the left lung base may be due to atelectasis although early infectious process is not excluded . No pleural effusion or pneumothorax is seen . Cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Subtle patchy opacity at the left lung base may be due to atelectasis although early infectious process is not excluded .