Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a new opacity in the retrocardiac region that effaces visualization of the medial hemidiaphragm as visualized on the PA view . Elsewhere , the lungs remain clear . There are no pleural effusions or pneumothorax . The cardiac , mediastinal and hilar contours appear stable .
    OUTPUT:
    
Medial left base opacity suggesting pneumonia in the appropriate context .