Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle lingular opacity could be due to atelectasis however , early infectious process is not excluded in the appropriate clinical setting . The lungs remain hyperinflated , suggesting chronic obstructive pulmonary disease . No pleural effusion is seen . There is no evidence of pneumothorax . Cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Subtle lingular opacity , best seen on the lateral view , could be due to atelectasis however , early / mild infectious process is not excluded in the appropriate clinical setting .