Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a moderate - to - large dependent left lower hemithorax pleural effusion which appears to have slightly increased in size compared to the study on ___ and is responsible for associated left lower lobe atelectasis . The right lung is clear . There is no evidence of mediastinal shift , suggestive of left lower lung volume loss . There is no evidence of a pneumothorax . The visualized osseous structures are unremarkable .
    OUTPUT:
    
Slight interval increase in the left lower hemithorax pleural effusion . The right lung is clear .