Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since prior exam . There has been an interval increase in the patchy opacification at the left base , which on the lateral view , localizes to the left lower lobe . The lungs are otherwise clear . There is no pulmonary edema , pleural effusion or pneumothorax . The mediastinal contours are normal . The heart is moderately enlarged , and unchanged from prior exams . A single - lead left pectoral pacemaker is unchanged .
    OUTPUT:
    
Minimal increase in the left lower lobe patchy opacification , which could be due to mild worsening chronic changes or a superimposed new infiltrate .