Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Moderate cardiomegaly is unchanged . Cardiomediastinal silhouette and hilar contours are otherwise normal . Subtly increased opacity compared to prior at the left lung base adjacent to the heart border with the posterior basal lateral correlate . Lungs are otherwise clear . Pleural surfaces are clear without effusion or pneumothorax .
    OUTPUT:
    
Subtly increased density at the posterior left lung base suspicious for pneumonia versus acute chest syndrome .