Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Opacity in the left lung base silhouetting the cardiac apex is consistent with infection . No substantial pleural effusion identified on this upright view . No pneumothorax . Heart size and cardiomediastinal contours are normal .
    OUTPUT:
    
Left lung base opacity concerning for infection . Followup after treatment may be obtained to assess for resolution .