Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared with the previous study , there is increased obscuration of the left hemidiaphragm with a left retrocardiac opacity , concerning for left lower lobe pneumonia . There is no pleural effusion or pneumothorax . The heart size is normal , and the thoracic aorta is tortuous .
    OUTPUT:
    
Obscuration of the left hemidiaphragm with a left retrocardiac opacity is concerning for left lower lobe pneumonia .