Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A large right - sided pleural effusion with balanced mass effect and probable associated atelectasis has developed since the prior radiographs . The left lung remains clear . The lateral view suggests a small pleural effusion on the left . There is no pneumothorax . A healed left posterolateral eighth rib fracture appears unchanged .
    OUTPUT:
    
Large new right - sided pleural effusion .