Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiomediastinal and hilar silhouettes are normal . Asymmetric opacity of the left lower lobe may be due to atelectasis , but given the clinical history , superimposed infection is considered . No pleural effusion or pneumothorax .
    OUTPUT:
    
1 . Left basilar opacity may be due to atelectasis , but superimposed infection is also possible given the patient 's clinical history . 2 . No evidence of lung hyperinflation .