Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest views were obtained with patient in upright position . Comparison is made with the next preceding similar study of ___ . The on previous examination identified small - sized right - sided apical hydropneumothorax has now decreased markedly and only a small apical pneumothorax persists on top of the right - sided large pulmonary mediastinal mass . Otherwise , the chest findings are unaltered , and the left - sided hemithorax is normal .
    OUTPUT:
    
Marked regression of previously remaining small post - interventional pneumothorax in right apical area .