Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal silhouette and pulmonary vasculature are unchanged since the prior examinations . A subtle left perihilar opacity is new from the prior exam . Appearance of the lungs is otherwise unchanged . . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
New left perihilar opacity , which may reflect an early focus of pneumonia or aspiration in the appropriate clinical setting . Followup PA and lateral radiographs of the chest are recommended for more complete evaluation when the patient 's condition permits .