Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is at the upper limits of normal or slightly enlarged . Cardiomediastinal silhouette and hilar contours are otherwise within normal limits . Trace blunting of the costophrenic sulci may represent trace effusions . Increased density in the posterior lung base on lateral view only without definite frontal correlate . Equivocal hazy density at the left lung base . Upper lung zones are clear . No pneumothorax .
    OUTPUT:
    
Mildly increased density in the posterior base on lateral view without definite frontal correlate may represent a pneumonia . Possible trace effusions .