Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . There is a subtle consolidation of the left base which is similar to prior and may represent atelectasis or possibly early pneumonia . No pleural effusion or pneumothorax is seen .
    OUTPUT:
    
Left basal opacity which may represent atelectasis or early pneumonia in the appropriate clinical setting .