Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a large left - sided pleural effusion with slight rightward shift of mediastinal structures , similar to the prior study allowing for differences in technique including positioning . There is probable associated extensive atelectasis of the left lung . Patchy right basilar opacity has a flat linear morphology suggestive of atelectasis , which is also similar . There is no pneumothorax or definite pleural effusion on the right .
    OUTPUT:
    
Similar large left - sided pleural effusion .