Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest were obtained . A vague opacity is seen in the left lower lung which could represent a very early pneumonia . Retrocardiac opacity is also noted which is most compatible with a hiatal hernia . No large pleural effusions are seen . Cardiomediastinal silhouette is stable . No definite signs of CHF , though subtle Kerley B lines may indicate an element of mild interstitial edema . Bony structures are intact .
    OUTPUT:
    
Hiatal hernia , subtle opacity in the left lower lung , question early pneumonia . Mild interstitial edema .