Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left lung volume loss and mild mediastinal shift to the left is consistent with post left lower lobectomy . There is a single left - sided chest tube with its tip reaching to the left apex . Left apical pneumothorax is mild - to - moderate . There is no demonstrable pleural effusion . Mediastinum is unremarkable .
    OUTPUT:
    
Small - to moderate - sized left apical pneumothorax . No effusion or lung opacities of concern .