Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright radiograph of the chest demonstrates persistent small left - sided apical pneumothorax , which is not significantly changed from the prior study . Again seen is mild left - sided atelectasis , also unchanged . A chest tube projects over the left hemithorax . The right lung is clear . The cardiomediastinal and hilar contours are unchanged . A left - sided PICC ends at the cavoatrial junction .
    OUTPUT:
    
Stable appearance of small left - sided apical pneumothorax .