Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle patchy left base opacity is seen , which may be due to atelectasis , but but an early / mild pneumonia is not excluded in the appropriate clinical setting . No pneumothorax is seen . There is no large pleural effusion . Cardiac and mediastinal silhouettes are stable and unremarkable .
    OUTPUT:
    
No evidence of pneumothorax . Subtle right base opacity could be due to atelectasis , but an early / mild pneumonia is not excluded in the appropriate clinical setting .