Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Only trace residual left pneumothorax remains after placement of a chest tube . Retrocardiac opacity likely represents persistent atelectatic lung and some smaller component of the previously large pleural effusion . The right lung is clear .
    OUTPUT:
    
Tiny residual left pneumothorax status post chest tube placement . Retrocardiac density likely secondary to persistent atelectatic lung .