Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is hazy opacity at the left lung base . The cardiomediastinal silhouette is unchanged with normal heart size and tortuous thoracic aorta . There is no pleural effusion or pneumothorax . A left chest pacemaker and leads are in unchanged positions . There is no free air under the diaphragm .
    OUTPUT:
    
Hazy opacity at the left lung base which may represent atelectasis or an early focus of pneumonia . Short - term followup radiographs may be helpful in this regard if the diagnosis is in doubt clinically .