Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP view of the chest provided . Again seen is a small - moderate size left apical pneumothorax , not significantly changed since study from 4 hours ago . There is no mediastinal shift . Similar atelectatic changes are seen in the left lung base . Chest tube is in unchanged position .
    OUTPUT:
    
Unchanged small - moderate left apical pneumothorax .