Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Upright portable radiograph of the chest demonstrates unchanged small left apical pneumothorax with no evidence of increased mediastinal shift . Otherwise , the right lung is similar in appearance and there is no other relevant change . Subcutaneous emphysema along the left lateral chest wall is likely due to previous chest tube placement .
    OUTPUT:
    
Stable small left apical pneumothorax .