Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low with increased density at the left lung base , likely representing a combination of known mass , effusion , and atelectasis ; consolidation can not be excluded . No pneumothorax is seen . The right lung does not demonstrate focal consolidation or pleural effusion .
    OUTPUT:
    
Left lower lung opacity , which likely represents a combination of known mass , effusion , and atelectasis ; consolidation can not be excluded .