Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is an indeterminate opacity in the left upper lobe lateral to the aortic arch . There is no focal consolidation , effusion , or pneumothorax . The cardiomediastinal silhouette is normal . Imaged osseous structures are intact . No free air below the right hemidiaphragm is seen .
    OUTPUT:
    
1 . No pneumonia . 2 . Indeterminate opacity in the left upper lobe may represent a nodule or superimposition of normal structures .