Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Moderate left - sided pleural effusion . The lungs are otherwise clear . The cardiomediastinal silhouette is unremarkable . No pneumothorax . No acute osseous abnormality .
    OUTPUT:
    
Moderate left - sided pleural effusion , can be reactive from pyelonephritis or infected pleural fluid such as empyema . Suggest close clinical and imaging follow up .