Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are relatively well expanded . Increased retrocardiac opacity compared to the prior study is compatible with developing / focal left lower lobe pneumonia . The cardiomediastinal silhouette is unremarkable . There is no pleural effusion , pneumothorax or pulmonary edema .
    OUTPUT:
    
Early left lower lobe pneumonia .