Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The previously described opacity in the right upper lobe is no longer visualized and may have been external to the patient . Lungs are clear except for localized bulla or blebs in the right lung apex with adjacent linear scarring , not appreciably changed since ___ . Heart size , mediastinal and hilar contours are normal . No pleural effusion . Scoliosis is noted .
    OUTPUT:
    
Resolution of right upper lobe opacity , which may have represented a structure external to the patient on the prior radiograph .