Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart appears mildly enlarged . The cardiac , mediastinal and hilar contours appear stable . There is similar mild relative elevation of the right hemidiaphragm . There is no pleural effusion or pneumothorax . The right lung remains clear . There is a medial retrocardiac opacity probably in the left lower lobe , better visualized on the two AP views compared to the lateral , not present before .
    OUTPUT:
    
Patchy retrocardiac opacity , probably pneumonia .