Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral chest radiograph is compared to prior radiograph dated ___ . Relative to prior study , cardiomediastinal and hilar contours are stable . Obscuration of the left hemidiaphragm and opacity in the left lung base persists from prior examination though less conspicuous . Lungs appear hyperexpanded and diaphragms flattened suggestive of emphysematous changes . There is a probable small left pleural effusion . There is no pneumothorax . There is possible minimal interstitial edema .
    OUTPUT:
    
Relative to prior radiograph dated ___ , there persists opacification at the left lung base , though less conspicuous and better aerated . Developing pneumonia can not be excluded . Lungs are otherwise mildly hyperinflated to suggest emphysematous changes .