Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is subtle increased opacity at the left lung base obscuring the left heart border also seen on the lateral view . Elsewhere , lungs are clear . Cardiomediastinal silhouette is otherwise unremarkable . No acute osseous abnormalities .
    OUTPUT:
    
Opacity at the left cardiophrenic angle which is felt most likely to be due to a prominent fat pad noting that parenchymal opacity in the lingula is not entirely excluded .