Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral radiographs of the chest once again demonstrate a right apical pneumothorax which has not changed substantially in size from the prior study . Aside from the stable appearance of the right hilar and mediastinal mass , the lungs are clear . There is no effusion or pulmonary edema . Elevation of the right hemidiaphragm is unchanged .
    OUTPUT:
    
Stable size of right apical pneumothorax .