Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is mild cardiomegaly , stable compared to exams dated back to at least ___ . The hilar and mediastinal contours are otherwise stable . There appears to be an interval increase in opacification at the retrocardiac region and left lung base which could be secondary to atelectasis ; however , an infectious process can not be excluded . There has been a slight interval increase in a chronic small right pleural effusion as well as mild right basilar atelectasis . There is no evidence of a pneumothorax .
    OUTPUT:
    
1 . Increased retrocardiac and left lung base opacification , likely secondary to atelectasis ; however , an infectious process can not be excluded . 2 . Slight interval increase in a chronic small right pleural effusion and mild right basilar atelectasis .