Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is subtle increased opacity in the left upper lung , particularly superolateral to the left hilum . There is no effusion or evidence of edema . The cardiomediastinal silhouette is within normal limits . No acute osseous abnormalities .
    OUTPUT:
    
Subtle increased opacity in the left upper lung on the frontal view which certainly could represent subtle pneumonia .