Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . There is no pleural effusion or a pneumothorax . Patchy opacity refers to the left lower lobe , but elsewhere the lungs appear clear . Small anterior osteophytes are noted along the mid thoracic spine .
    OUTPUT:
    
Opacity in the left lower lobe . Differential considerations include atelectasis , developing pneumonia or possibly aspiration in the appropriate setting .