Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single portable AP upright view of the chest was provided demonstrating increased opacity at the left lung base concerning for aspiration versus pneumonia . Given the associated volume loss in the left lower lung atelectasis also likely present . There may be an associated small pleural effusion . The right lung is clear . The cardiomediastinal silhouette is stable . No pneumothorax is seen . There are no acute bony abnormalities .
    OUTPUT:
    
Opacity at the left lung base likely represents a combination of atelectasis and aspiration / pneumonia . Possible small left effusion .