Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single AP chest radiograph was obtained . A moderate - to - large left pleural effusion and overlying atelectasis is roughly similar to prior imaging studies . There is no new consolidation , right effusion or pneumothorax . Mild cardiomegaly is similar .
    OUTPUT:
    
Moderate - to - large left pleural effusion .