Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . Endobronchial valves project over the left pulmonary hilum . Patient is known to have severe emphysema . A small left pneumothorax appears similar to the prior exam . No signs of tension . Mild left basal atelectasis persists . Right lung is clear . Cardiomediastinal silhouette is stable . Bony structures are intact .
    OUTPUT:
    
Small left pneumothorax without signs of tension . Mild left basal atelectasis . Severe background emphysema .