Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a left basal opacity , minimal but new , potentially representing atelectasis but pneumonia can not be excluded . No other focal consolidation is seen , and the lungs are clear of pneumothorax or pleural effusions . The heart size is normal . The mediastinal contours are normal .
    OUTPUT:
    
Left lower lobe opacity , potentially pneumonia , but atelectasis is a possibility .