Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Retrocardiac opacity silhouetting the left hemidiaphragm with air bronchograms concerning for developing pneumonia . Lung volumes remain low . No large pleural effusion or pneumothorax . Stable cardiomediastinal contours .
    OUTPUT:
    
Retrocardiac opacity with air bronchograms concerning for developing pneumonia